Gravity

Projectile Motion Lab: Using a Toy Gun Purpose: The purpose of this investigation is to measure the vertical displacement, or height of the launch, and the horizontal displacement, or range, travelled by a projectile (bullet from toy gun). Questions: What is the shape of the actual path travelled by a projectile? How closely does an actual projectile’s results follow the theoretical predicted results? Hypothesis: The shape of the path travelled by the projectile, in this case the bullet of the gun, is a parabolic.

This means that is a curvy shape due to the bullet being launched in the air (making curve go up) and the earth’s gravity pulling it down (making curve go down). As the height of the bullet’s release increases the the time to reach the ground will increase, and therefore the range of the bullet will increase. This is because the bullet’s vertical velocity will decrease later as the height is higher up, having a larger time, and therefore a larger range. Materials: Toy Gun Fake Bullets Metre Sick Stop Watch General Observations: A metre stick was used to measure the height and the range of the bullet.

A stop was used to determine the time it took for the bullet to reach the ground. As the bullet was released, its path was parabolic. This means that its was curvy because it was first int air, but the gravity pulled it back down to the surface. The toy gun was steadily held in my hand. The initial height was the distance from the gun to the surface used. The gun shot out the bullets at a fairly fast speed. As the height was increased, the more time the bullet took to reach the ground. As the height was increased, the range was also higher.

Analysis: Picture of the launcher: Height vs. Range graph- Refer to attached data in the back. Position vs. Time graph- Refer to attached data in the back. The graph results definitely support the hypothesis. This is because as the height of the toy gun was increased, the horizontal distance increased.

Also, as the horizontal distance of the bullet increased, so did the time (vice- versa). The graphs were very similar due to the horizontal distance (cm) being constant on the y- axis of the graph. In the Horizontal Distance vs. Time graph, the time represented the corresponding heights of the Horizontal Distance vs Height graph. Making the graphs very similar. Determining the Vi of the Bullet: Vi = aav x ? t aav = -9. 81 m/s? ?t = 3. 19 seconds Vi = -9. 81 x 3. 19 Vi = 31. 3 m/s [v] *Therefore the initial velocity of the bullet is 31. 3 m/s [v]. Theoretical Ranges of the Bullet:

Sources of error: The first source of error was the toy gun’s bullet were not perfectly a cylinder. Since the bullets we made out of plastic foam there some ripped edges. This would definitely give a slightly inaccurate result sine the bullet would not consistently travel in the same way as it is going in a parabolic path. This would cause some twisting and turning of the bullet since the rips would collect air and make the bullet therefore move around (sort of like air pockets). The main problem with this is that the bullet is not consistently travelling in the exact same way.

Another source of error was that since the gun was shot from a human being’s hand it is really tough to keep the gun at the same angle (zero degrees) as it is shot. If the angle of the gun is not consistently shot at the same angle it will definitely impact the results because the horizontal distance (range) of the bullet will be different each time. If the gun has an angle pointing downward, the range will decrease. The bullet will be in the air for a smaller amount of time, covering less ground. If the gun is pointing upward the range will increase.

The bullet will be in the air for a longer period of time, covering more ground. There can be ways though to fix these sources of errors. For the first one where there were rips in the bullet, what one can do to fix the bullets is use tape to cover up the holes. Or, a better solution would to buy new, fresh bullets where there are no bend, rips or chance of disfunction. To make sure that the bullets angle is constant after each shot, what one can do is use a stand to place the gun in. This would make sure that the gun is not pointing down or upward, giving very accurate data of the range. Conclusion:

All projectiles travel in a parabolic path. Projectile motion is the motion of an object who’s path is affected by the force of gravity. Everything is affected by gravity, but it profoundly alters the motion of objects that are thrown or shot upward. The arching of the bullet in this experiment is caused by gravity, as well as its falling motion in general. Gravity causes change in the vertical velocity of the projectile. Objects experiencing projectile motion have a constant velocity in the horizontal direction, and a constantly changing velocity in the vertical direction. Thus, this is causing the parabolic shape.

The actual projectile’s results were really close to the theoretical results in this case. There were no outliers in the range. If the theoretical range and the actual range were not close it would be due to the tools used to measure the time and the distance. A metre stick was used to determine the horizontal range for the experiment. This is very inaccurate because the bullet dropped way to fast to see the actual landing spot. The landing spot was based on the eye. Also since a timer was used to determine the time of the bullet’s range this is again very inaccurate since the bullet dropped way to fast to use a stop watch.

Overall, the results in this case were luckily extremely close and accurate having a maximum percent error of 0. 00 8%. The reasons for the experimental error was mainly due to the tools used to measure data and, the inconsistency of the angle of the gun. As stated earlier a metre stick was used to determine the horizontal range for the experiment. This is very inaccurate because the bullet dropped way to fast to see the actual landing spot. The landing spot was based on the eye. Since a timer was used to determine the time of the bullet’s range this is again very inaccurate since the bullet dropped way to fast to use a stop watch.

Again as stated earlier, if the angle of the gun is not consistently shot at the same angle it will definitely impact the results because the horizontal distance (range) of the bullet will be different each time. If the gun has an angle pointing downward, the range will decrease. The bullet will be in the air for a smaller amount of time, covering less ground. If the gun is pointing upward the range will increase. The bullet will be in the air for a longer period of time, covering more ground.

Freefall and Projectile Motion Introduction and Objectives This lab experiment was done to determine the characteristics of free fall and projectile motion in Physics. The motion in which a body is thrown or projected is called Projectile motion while free fall is any motion of a body where gravity is the only force acting upon it, at least initially. In this experiment, a photogate, a chopper, and a Universal Lab Interface were used to determine the free fall motion of the chopper as it was released.

A ball, carbon paper, and an L-shape projector were also used to determine the range of projectile motion of a ball being released from a horizontal yet slightly vertical slope. At the end of the experiment, one will know how velocity and time affect the acceleration of a free falling object and its projectile motion. Thoery Aristotle stated in his theory of motion that the fall of a heavy object toward the center of the earth is a natural motion because the object is just returning to its natural place.

He also stated that heavy objects fall faster than lighter ones because increase in the rate of motion is proportional to the weight of the object. Galileo’s theory states that the when a ball was rolled down an inclined plane at fixed angle? ; the ratio of the distance covered to the square of the corresponding time was always the same, but that when the angle of inclination is changed, the constant also changes but remains the same for the same angle. The constant d/t2 is also the constant for falling object (refers to the acceleration due to gravity).

The experimental range used in the experiment is 45 cm, and the expression of the range of the projectile was found in terms of Vg and h. The horizontal distance traveled by the projectile for the total time of flight is given simply by R=vxt where t is the total time of flight and vx is the constant horizontal velocity. The time of flight was found using the equation for vertical motion, which is y=yi + viyt-1/2gt^2. After each experiment, the Logger Pro software determined the curve of the time vs velocity graph to determine which had a better Linear fit, either the Quadratic or the Linear curve. http://physicse-book8. blogspot. com/) Results and Discussion A. Free fall Motion Trial NumberAcceleration Value (m/s^2) 119. 32 219. 46 319. 57 419. 61 520. 58 Ave acceleration (m/s^2)19. 71 The quadratic curve proved to give a better fit because the points formed a curved line and are constantly increasing. The percentage error calculated . 56. This is because the heights from where the picket fence was dropper was different in every trial. B. Projectile Motion Highest Point TrialDistance (m)Velocity (m/s) 1. 455. 98 2. 461. 04 3. 435. 97 4. 435. 96 . 441. 01 Mid-Point TrialDistance (m)Velocity (m/s) 1. 365. 79 2. 36. 793 3. 365. 78 4. 368. 78 5. 358. 79 Conclusion This lab experiment proved helpful in understanding free fall. It was shown that under the influence of gravity, an object falls on its own with its velocity accelerating at a constant pace. It is said that when the only force acting on an object is the Earth’s gravitational force,it is in free fall. There cannot be any other force acting upon it, especially air resistance, which should either be absent or ignored by its minute size.

The force of gravity on an object is nearly constant when the object in free fall is near the earth’s surface. Because of this, the object accelerates downward at a constant rate. This acceleration is usually represented with the symbol g. In this experiment, a precise timer was connected to the computer and a Photogate was used to measure the acceleration due to gravity. “The Photogate has a beam of infrared light that travels from one side to the other. It can detect whenever this beam is blocked. ” A Picket Fence or a chopper, a piece of clear plastic with equally spread out black sections on it, was dropped. As the Picket Fence passes through the Photogate, the computer will measure the time from the leading edge of one bar blocking the beam until the leading edge of the next bar blocks the beam. ” This timing continues as all eight bars pass through the Photogate. From these measured times, the program will calculate the velocities and accelerations for this motion and graphs will be plotted. http://www. waukeshasouth. com/physics1/photo. html http://www. oppapers. com/essays/Picket-Fence-Free-Fall/567967

This lab was based on projectile motion and it was to prove the theory that was covered in lecture 5 to be correct. When dealing with projectile motion, it is the theory that when an object has been fired from its starting point into the air, it will come under the influence of gravity and is attracted to ground with an acceleration of g m/s squared.

In the lab a projectile launcher was used to project two steel balls, one in the horizontal direction and one in the vertical direction. The ball that was launched in the vertical direction was ball 1 and the ball that was launched in the horizontal direction was ball 2. The purpose of this experiment was to investigate projectile motion through the use of a vertical acceleration apparatus which shows the independence of vertical acceleration from the horizontal velocity.

Projectile motion is a form of motion in which an object or particle (called a projectile) s thrown obliquely near the earth’s surface, and it moves along a curved path under the action of gravity only. The path followed by a projectile motion called its trajectory. Projectile motion only occurs when there is one force applied at the beginning of the trajectory, after which there is no force in operation apart from gravity. Introduction: Part B Part B of the lab was on Tractive Forces. Tractive force means the force available at the contact between the drive wheel tyres and road is known as ‘tractive effort’ or tractive force’.

As used in mechanical engineering the term tractive force can either efer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. The published tractive force value for any vehicle may be theoretical”that is, calculated from known or implied mechanical properties”or obtained via testing under controlled conditions. The example that was taken in the lab was of a train of 3 parts that were coupled together by couples (T 1) and (T2).

The purpose of this lab was to prove the theory covered in lecture 6 was correct and to see the relationship between force, mass and cceleration in tractive forces which comes from Newton’s 2nd law. We know that force = mass x acceleration and we also were giving the conditions to which the train was under. Table 1, Part A: recorded and calculated data Measured time and distance for the vertical ball and the horizontal ball projected from projectile launcher. Test 1st Ball (vertical) 2nd Ball (horizontal) Distance (s) (m) Time of flight (t) 0. 5 0. 93 0. 6 1. 38 0. 4 0. 51 1. 46 0. 43 0. 56 1. 36 0. 35 0. 57 1. 34 0. 60 0. 68 1. 39 0. 0 7 0. 40 0. 54 1 . 45 8 0. 28 1 . 31 9 0. 30 0. 47 10 1. 32 Average values 0. 391 1 . 387 Table 2, part A: Calculated Horizontal velocity, acceleration due to gravity, the % difference in the value of gravity, and the Vertical velocity. Horizontal velocity (Vh) (calculated) 2. 57 rrvs Acceleration due to gravity, g (calculated) 6. 38 m/s squared % difference in the value of g -34. 96% Vertical striking velocity (W) (calculated) 3. 83 rms (Horizontal velocity) S = Vx T therefore S = 1. 39 = 2. 57 m/s T 0. 54 (Acceleration due to gravity) Sv = IJvT – 1 g(t)squared 2 Therefore = 2 (0. 93) squared T squared 0. 54 squared = 1. 86 = 6. 378 = 6. 8 rms 0. 2916 0. 2916 (% difference in the value of g) % difference = Calculated -g x 100 . 81 (Vertical striking velocity) V=U+GXT v = o + 3. 83571 v = 3. 83 rms Discussion part A =6. 38-9. 81 x 100 In this lab that was completed it was shown that the theory behind projectile motion is correct. It was proven that both balls came under the influence of gravity once they left the projectile launcher and that they were both attracted to ground. The two balls were launched from the same vertical height but the ball number 2 that was travelling in the horizontal direction travelled a further distance than ball number 1 in the vertical direction.

Even though ball number 2 travelled a further distance the wo balls will hit the ground at the same time as they both come under the same force of gravity however this was not shown in our table 1 (Fig 1) because their was human errors such as, two people starting the stop watches at different times, the person pressing the trigger mechanism was releasing the balls faster sometimes than other times even though we would start the stop watches on the count of 3. The other factors that had to be taken into consideration is, if the projectile launcher was at any sort of an angle due to the work bench not been balanced or level or an even surface.

However the readings that were taken were still very close to each other so experiment the initial velocity of each ball was O m/s. To calculate the acceleration due to gravity we manipulated the equation to find (g) gravity. When dealing with projectiles, we use the same equations as linear motion but the (a) for acceleration is replaced or substituted with (g) for gravity. The acceleration due to gravity was 6. 38 m/s squared. In theory this acceleration should have been 9. 81 m/ s squared but due to the human errors that occurred during the experiments there was a difference of -3. m/s squared these % errors came from miscalculating of the time taken for the balls to hit the ground and the distance travelled by the horizontal ball. When the steel ball number 2 is projected from the projectile launcher in the horizontal direction, the time it takes for the steel ball to hit the ground is independent of its initial horizontal velocity, the steel ball will continue to move in the horizontal direction with the same horizontal velocity in which it was projected from the projectile launcher with because there is no acceleration so it stays at a constant velocity.

The distance that the steel ball number 2 travels in the horizontal distance before it hits the ground is dependent on the time of flight and the horizontal velocity that it was projected with. Projectile motion only occurs when there is one force applied at the beginning of the trajectory, after which there is no force in operation apart from gravity, this was proven in the experiment as ball number 1 was let fall from a height with no other force applied and ball number two was projected with a horizontal velocity from the projectile launcher and both balls were attracted to ground as they came under the nfluence of gravity.

We found the value of acceleration using the average vertical height in which the ball was projected from and used the average horizontal time in which it took ball number two to hit the ground as ball number two was projected with an horizontal velocity it still should hit the ground at the same time as ball number one does as there both under the same force of gravity. If our measurements and calculations were 100% we should have got an acceleration of 9. 81 m/s squared. The horizontal component of the velocity of the object remains unchanged throughout the motion.

The vertical component of the velocity increases linearly, because the acceleration due to gravity is constant. It is important to note that the Range and the Maximum height of the Projectile do not depend upon mass of the projected body. The Range and Max Height are equal for all those bodies which are thrown by same velocity and direction. Air resistance does not affect displacement of a projectile; this is why we do not take the mass of the balls into consideration or the mass of any objects when dealing with projectiles. This experiment proves and supports the theory behind projectile motion to be correct.

We do not take the mass of the balls or bodies into consideration when dealing with projectile motion as the air resistance does not affect the displacement of the projectile. The range and height are equal for all bodies which are thrown by the same velocity and direction. There was a small difference in calculating the acceleration due to gravity, this was because of the different readings and human errors that took place during the experiment. Both balls come under the influence of the same gravity and are attracted to ground and should hit the ground at the same time.

In theory both balls should hit the ground at the same time, but because there were two people using stopwatches to record the times taking there was going to be a difference in the readings and calculation. The horizontal distance ball number two travels before it hits the ground is dependent of the time of flight and the horizontal velocity of projection. Ball number two will travel at the same horizontal velocity because there is no acceleration or any other force applied. The vertical component of the velocity will increases linearly because the acceleration due to gravity is onstant, so it picks up speed as it is falling from a height.

A Survey of the Background and Development of English Literature from the Earliest Time to Eighteen Century Contents 1. What is Literature? 2. Why the Knowledge of English Literature’s history is important 3. Distinct phases from Earliest to Modern Age 4. Brief survey of ages before Eighteen Century • Anglo-Saxon period • The Medieval period • The Renaissance period • The Puritan period • The Restoration period 5. A panorama of Eighteen century • General view of eighteen century • Social aspects • Religious aspects • Characteristics of eighteen century • Literary Critics of the age • Chronology of the writers of the age

What is Literature? The production of written works, having excellence of form or expression and dealing with ideas of permanent interest is called literature. Literature is one of the Fine Arts like, • Music • Dance • Painting • Sculpture. As it is meant to give aesthetic pleasure rather than serve any utilitarian purpose. It consists of great writings which, what ever their subjects are , notable for literary form or expression. Life, Society and Nature are the subject matters of literature. There is an intimate connection between literature and life, which provides the raw material on which literature imposes an artistic form.

Why the Knowledge of English Literature’s history is important? English literature is one of the richest literatures of the world, the literature of a great nation which has vitality, rich verity and continuity. As literature is the reflection of society, the various changes which have come about in English society, from the earliest to the modern times, have left their stamp on English literature thus in order to appreciate the true sense and taste of literature the knowledge of various phases of English literature, English society and political history of the land is essential.

When we study the history of English literature from the earliest to modern times, we find that it has passed through certain definite phases, each having marked characteristics. These phases may be termed as “Ages” or “Periods” and divided into different section according to their characteristics. There are five ways to identify the different eras of English Literature. Distinct phases from Earliest to Modern Age: 1. Phases which are named after the Central Literary figures. • Chaucer • Shakespeare • Milton • Dryden • Pope • Johnson • Wordsworth • Tennyson • Hardy : Periods named after the Rulers of the time. • Elizabethan Age • The Jacobean period • The Age of Queen Anne • The Victorian Age • The Georgian Period 3: simple partitions named after literary movements • Classical Age • Romantic Age 4: While other after certain important historical eras as, • Anglo-Saxon period • The Medieval period • The Renaissance period • The Puritan period • The Restoration period 5: Named by the p of Time • The Seventeen Century Literature • Eighteen Century Literature • Nineteenth Century Literature • Twentieth Century Literature

Brief survey of ages before Eighteen Century: The Old English Period or the Anglo-Saxon Period refers to the literature produced from the invasion of Celtic England by Germanic tribes in the first half of the fifth century to the conquest of England in 1066 by William the Conqueror. During the Old English Period, written literature began to develop from oral tradition, and in the eighth century poetry written in the vernacular Anglo-Saxon (also known as Old English) appeared. One of the most well-known eighth century Old English pieces of literature is Beowulf, a great Germanic epic poem.

Two poets of the Old English Period who wrote on biblical and religious themes was Caedmon and Cynewulf. The Middle English Period consists of the literature produced in the four and a half centuries between the Norman Conquest of 1066 and about 1500, when the standard literary language, derived from the dialect of the London area, became recognizable as “modern English. ” Prior to the second half of the fourteenth century, vernacular literature consisted primarily of religious writings. The second half of the fourteenth century produced the first great age of secular literature.

The most widely known of these writings are Geoffrey Chaucer’s The Canterbury Tales, the anonymous Sir Gawain and the Green Knight, and Thomas Malory’s Morte d’Arthur. While the English Renaissance began with the ascent of the House of Tudor to the English throne in 1485, the English Literary Renaissance began with English humanists such as Sir Thomas More and Sir Thomas Wyatt. In addition, the English Literary Renaissance consists of four subsets: The Elizabethan Age, the Jacobean Age, the Caroline Age, and the Commonwealth Period (which is also known as the Puritan Interregnum).

The Elizabethan Age of English Literature coincides with the reign of Elizabeth I, 1558 – 1603. During this time, medieval tradition was blended with Renaissance optimism. Lyric poetry, prose, and drama were the major styles of literature that flowered during the Elizabethan Age. Some important writers of the Elizabethan Age include William Shakespeare, Christopher Marlowe, Edmund Spenser, Sir Walter Raleigh, and Ben Jonson. The Jacobean Age of English Literature coincides with the reign of James I, 1603 – 1625.

During this time the literature became sophisticated, somber, and conscious of social abuse and rivalry. The Jacobean Age produced rich as well as the King James translation of the Bible. Shakespeare and Jonson wrote during the Jacobean Age, as well as John Donne, Francis Bacon, and Thomas Middleton. The Caroline Age of English Literature coincides with the reign of Charles I, 1625 – 1649. The writers of this age wrote with refinement and elegance. This era produced a circle of poets known as the “Cavalier Poets” and the dramatists of this age were the last to write in the Elizabethan tradition.

The Commonwealth Period, also known as the Puritan Interregnum, of English Literature includes the literature produced during the time of Puritan leader Oliver Cromwell. This period produced the political writings of John Milton, Thomas Hobbes’ political treatise Leviathan, and the prose of Andrew Marvell. In September of 1642, the Puritans closed theatres on moral and religious grounds. For the next eighteen years the theatres remained closed, accounting for the lack of drama produced during this time period.

The Neoclassical Period of English literature (1660 – 1785) was much influenced by contemporary French literature, which was in the midst of its greatest age. The literature of this time is known for its use of philosophy, reason, skepticism, wit, and refinement. The Neoclassical Period also marks the first great age of English literary criticism. Much like the English Literary Renaissance, the Neoclassical Period can be divided into three subsets: the Restoration, the Augustan Age, and the Age of Sensibility.

The Restoration, 1660 – 1700, is marked by the restoration of the monarchy and the triumph of reason and tolerance over religious and political passion. The Restoration produced an abundance of prose and poetry and the distinctive comedy of manners known as Restoration comedy. It was during the Restoration that John Milton published Paradise Lost and Paradise Regained. Other major writers of the era include John Dryden, John Wilmot 2nd Earl of Rochester, and John Locke. The English Augustan Age derives its name from the brilliant literary period of Virgil and Ovid under the Roman emperor Augustus (27 B. C. – A.

D. 14). In English literature, the Augustan Age, 1700 – 1745, refers to literature with the predominant characteristics of refinement, clarity, elegance, and balance of judgment. Well-known writers of the Augustan Age include Jonathan Swift, Alexander Pope, and Daniel Defoe. A significant contribution of this time period included the release of the first English novels by Defoe, and the “novel of character,” Pamela, by Samuel Richardson in 1740. During the Age of Sensibility, literature reflected the worldview of Enlightenment and began to emphasize instinct and feeling, rather than judgment and restraint.

A growing sympathy for the Middle Ages during the Age of Sensibility sparked an interest in medieval ballads and folk literature. Another name for this period is the Age of Johnson because the dominant authors of this period were Samuel Johnson and his literary and intellectual circle. This period also produced some of the greatest early novels of the English language, including Richardson’s Clarissa (1748) and Henry Fielding’s Tom Jones (1749). General view of eighteen century:

In history English literature the period of over one hundred years from (1660-1789) is variously termed as Augustan Age, Pseudo-classical age or Neo-Classical; Age, and age of Queen Anne. Matthew Arnold as Age of Prose and Reason it is also knows as age of Good Sense, age of Good Taste and age of Right Reason. The term Augustan was chosen by the writers of eighteenth century themselves, who saw in Pope, Addison, Swift, Johnson, Burke, the modern parallels to Horace, Virgil, Cicero and other brilliant writers who made roman literature famous during the reign of Emperor Augustus.

Eighteen century is called new Classical age on the account of three reasons: a) The writers of eighteen century tried to follow the noble and simple methods of great ancients like Homer and Virgil that’s why they were called Neoclassicist. b) During eighteen century there was an abundance of literary productions there for critics termed as neoclassical age. c) During this period English rebelled against the exaggerated and fantastic style of writing prevalent during the Elizabethan and Puritan ages and they demanded that Poetry, should follow exact rules. n this they were influenced by French writers specially Boileau and Rapin. Therefore this period is known as neoclassical age. In eighteen century there was a completion of the reaction against Elizabethan romanticism. This reaction had started in seventeen century with Denham, Waller and Drden. Eighteen Century is the age of social, political, religious and literary controversies. Critical; spirit was aboard and men stop taking things for granted. Great stress was on reason and intellect sin. Notice the difference in age between Franklin and Edwards. 706 for Franklin and 1703 for Edwards. They are only three years apart, but they live in different eras. It was a choice that they made. You can be like Jonathan Edwards even now, and some people are. Ben Franklin is part of new movement, one that arises in Europe then moves out from there. This is called the Enlightenment, also known as the Age of Reason or the Neo-Classical Era. –  This period goes by the names “the Enlightenment,” “the Age of Reason,” and “the Neo-Classical Age. ”        – There was a great turning away from religion as primary way of life. People had been caught up in religious schism and sometimes outright warfare from 1534, the year Henry VIII split away from the Catholic church, until the Glorious Revolution of 1589. England now turned its attention to politics and scientific/logical analysis & reason. – Belief had been based on authority; restoration brought the scientific method. – Scientific method – beliefs should be proven through repeated experiments. Until now, one was to trust the pronouncements of some authority. In religion, you accepted the dictates of the church; in science, you would turn to a recognized authority like Aristotle, Ptolemy, etc.

Your own experience could mislead you. Chaucer’s Wife of Bath trusted experience over authority, but she was wrong to do so. In this era, she would be right. • Copernicus & Galileo trusted their own experience, their observations of the stars, over the authority of Ptolemy. They concluded that the world circled the sun rather than the other way around. • Newton discovered the laws of gravity, motion, & created a new branch of mathematics – calculus. A valid experiment would be repeatable. Thus others who turned telescopes toward the skies should observe the same things Copernicus & Galileo did. people wanted proof; did not want to accept an idea as true just because some person of authority said. The big name for the Enlightenment is Sir Isaac Newton. He discovered gravity; this is the calculus branch of mathematics. Newton was a great thinker. He discovered the idea of gravity that bodies attract to one another based on their mass. He discovered a principle, why things fall to the earth. For Edwards, you fell to the earth because of God. Now we have another explanation, a natural explanation, it is the pull of gravity.

In the religion of these people, once you discover the way that the planets move around the sun and the reason of this is gravity, then you eliminate the need for supernatural intervention. In the Ptolemaic system understood by the medieval Christian, angels were responsible for that making the sun, the moon, and the stars go around. Could an angel be up on the moon pushing it? Is there any way to disprove it? It could be possible, we cannot disprove it. Do we really think there are angels? No, because gravity was a sufficient explanation. We do not need the angels anymore; we have gravity now.

They could be there but they aren’t necessary. In the idea of cutting away that which is unnecessary, moving from that which is complex to that which is simple in science is not as Occam’s razor. Occam was an English priest and a scientist. Occam’s razor is the idea that you cut away any unneeded part of your hypothesis. The thrust of Enlightenment was to search for natural explanations for things in the scientific method. The idea of supernatural becomes something of a scandal, something of a great difficulty; why would God need to intervene?

If Mars was doing loops out there, then God would need to do so, but He made a more simple and elegant system which operates on its own. The universe is like a giant clock and God is the master clock maker. In this period, they loved to make clocks. Clocks were emblematic of the universe. You could tell time by the way the planets move around the sun. They’re only in this position every so many years. Based on that, if you’ve been out time traveling and you come flying into the Solar System, you can take a snapshot of where the planets are and figure out when it is.

It moves like a giant clock and they were discovering this. These aren’t random or odd motions up in the sky, they are very regular. So God created a world that operates according to laws, natural law. This means that He does not need to intervene. They had their own sort of religious expression. They were called the Deists. Deism is sort of a natural religion. That is it’s based on observation of what we can see. Another element of this Enlightenment is the idea that we should be able to see the evidence for ourselves and judge it for ourselves. A movement away from authority.

Before, if you wanted to prove a scientific theory, you would consult Hypocrites and Aristotle. You would put together your quotations, and it’s proven because you quoted the proper authorities. In religious matters, you quote the Bible, and the Bishops, and the theologians, the proper authorities. Now they say move toward your own individual ability. We see that somewhat also in the early stages of the Puritan movement, but this is expressed very differently. If I turn down a light switch, it will turn the light off. If you turn the switch, will it do the same thing?

If it is scientifically valid, it is universal; anybody can turn the light off. The one thing an experiment has to be is repeatable. The idea of special revelation goes away. We now have the appeal to general revelation. The goal is to have a religion based on stuff that is accessible to all of us. You don’t have to be in a certain place at a certain time; anybody anywhere can repeat this experiment. Social aspects: There was a rise of a trading community in the early eighteen century England. Most of the traders were Whigs and most of the landed gentry and nobility were Tories.

The clash between these two parties was not only political but social two. Eighteen century is known in the social history of England for the rise of the middle classes with the unprecedented rise in trade and comers the English were becoming increasingly wealthy and many hither to poor people were finding theme selves in the rank of respectable burgesses. These nouveaux riches were desirous of giving themselves and aristocratic touch by appearing to be learned and sophisticated like there traditional social superiors- the landed gentry and nobility.

This class of readers had hitherto been neglected by high brow writers. the literary works previous to the eighteen century were almost in variably meant to be the reading of the higher strata of society. Only popular literature such as Ballad, catered for the lower rungs. The up and coming middle classes of the eighteen century demanded some new kind of literature which should be in conformity with there temper and be designed as well to voice there aspirations as to cater for there taste. England was than becoming a country of small and big traders and shop keepers.

Some new type of literature of literature was demanded and this new type must expressed the new idle of the eighteen century, the value and the importance of the individuals life to tell men, not about knights to kings but about themselves, about their own thoughts and motives and struggles and the results of action upon their own characters. Religious aspects: The fact that religion is not only concerned with spirituality and morality but also with physical and psychological health is reflected in the teaching of most religious traditions in the world.

Eighteen century was the age of the speared of natural religion or Deism. Deists believed in the existence of God but disbelieved in any revealed religion, not excepting Christianity. Even in religion, reason and nature ruled the roost. People were also talking about” natural morality” the doctrine of the reason loving deists were repudiated by arthropods ethnologists. Characteristics of eighteen century: 1. Reason and rationality 2. Realism and precision 3. Rise of periodical press 4. Rapid development of prose 5. Prosaic poetry 6. Augustan themes 7. Development of satire 8.

Evolution of novel 9. Deficient in drama Reason and rationality: Pope and his followers gave much importance to reason in their modes of thinking and expressing. In the eighteen century reason was exalted. The main characteristic of neoclassical age is a general searching after rationality. This search which started in the age of Dryden culminated in the age of Pope. This reign of reason and common sense continued in to the middle of the century when the new ides and voices appeared and the precursors of the English romantics of the nineteenth century appeared on the scene.

Al the important writers of the neoclassical age Swift, Pope and Dr. Johnson glorified reason. Realism and precision: The two main characteristics of the restoration period-Realism and precision were carried to further perfection during eighteen century. They are found in their excellent form in the poetry of Pope who perfected the heroic couplet and in the prose of Addison who developed it into a clear, precise and elegant form of expression. Rise of Periodical press: With the rise of the periodical press in the begging of the eighteen century, the essay took a long stride forward.

Addison and Steele wrote social essays, their aim was social reform and to censor the manners and morals of the age, more particularly the frivolities of the female sex. Rapid development of prose: As eighteen century was the age of social, political and literary controversies in which the prominent writers took an active part and the large number of pamphlets, journals and magazines were brought out in order to cater to the growing need of the masters, who had began to read and take interest in these controversial matters.

Poetry was considered inadequate for such a task and hence there was a rapid development of prose. Prosaic poetry: Infect poetry also had become prosaic because it was no longer used for lofty and sublime purposes but like prose its subject matter had become criticism , satire, controversy and it was also written in the form of essay which was the common literary form. The chief glory of the age was therefore not poetry but prose. It was the age of satiric and argumentative and reflective poetry. Hardly any lyric or sonnet worth mentioning belongs to the period.

There is a growth of artificial poetic diction, and the language of poetry is cut off from the language of everyday use. Artificial themes: The Augustan literature was mainly intellectual and rational, deficient in emotion and imagination. It dealt exclusively with the artificial life of the upper classes of the city of London and its form and diction was as artificial as its theme. It had no feeling for nature and no feeling for those who lived out side the narrow confines of fashion able London society. Development of satire:

Satire developed as a form of literature during this age. Mostly prose writers wrote satires on the contemporary issues. The aim was the social reformation and to criticize the attitudes and behaviors of the age. The Whigs and the Torries members of the two important political parties which were constantly contending to control the government of the country- used and rewarded the writers for satirizing their enemies and undermining their reputation. Evolution of novel: New literary form novel was developed.

Realism of the age and development of the excellent prose style helped in the evolution of the novel. Between the period (1740 and 1800) novels of all kinds were written. Four main novelists of the eighteen centuries are Richardson, Smollett, Sterne and Fielding. Deficient in drama: Eighteen century was deficient in drama because the old puritanic against the theater continued and the court also withdrew its patronage. Gold Simith and Sheridan were the only writers who produced plays having literary merit. Literary Critics of the age:

According to Oxford new English dictionary criticism is defined as” the art of estimating the qualities and character of literary or artistic work”. It also quotes Dryden’s definition of criticism as “a stander of judging well”. “Whoever thinks a faultless piece to see, Thinks what ne’er was, nor is, nor e’er shall be. ” (From An Essay on Criticism) Three major critics of the neoclassical age are Dryden, Pope, and Johnson. Dryden as a critic: As a student of the principles of criticism, Dryden broke entirely new grounds.

He penetrated more deeply then any critic had yet done into the problem of the character of poetry, and the function and meaning of a conscious work of art. In his work we have not only criticism, but criticism becoming conscious of itself, analyzing its objects with sympathy and understanding, and knowing its purpose. He always had an open mid on all literary problems and refused to be influences by the pronouncements of the French critics like Boileau, who were bent on curtailing the freedom of literary composition as well as judgment.

He found no harm in the mixture of tragedy and comedy which some English dramatists had attempted, nor did he blame the “variety and copiousness” of the English plays, simply because they did not conform to the French ideal of singleness of plot. Even to Aristotle he refused to render servile obedience. Though living in the age when Aristotle’s theories were widely admired, he had the courage to declare” “it is not enough that Aristotle had said so, for Aristotle drew his models of tragedy from Sophocles and Euripides; and, if he had seen ours, might have changed his mind. Dryden was the first critic to introduce the nation that literature is an organic force which develops with the development of a nation. It is not a static but dynamic force which expresses the impulse of each new age in a manner suited to its growth, and changes according to the change in the disposition of the people. The critic, therefore, should study the literature of an age in the context of its environment, and not follow blindly the rules laid down by the ancient critics like Aristotle.

This, no doubt, was a revolutionary development in the field of criticism which in the seventeenth century was dominated by the classical school of critics. Though Dryden expressed his critical opinions in the prefaces to his own literary productions, in critical studies of great writers, as well as in some critical essays as Apology for Heroic Poetry, yet his greatest critical work in his famous. An essay of Dramatic Poesy (1668). It is the most ambitiously constructed critical document of his career and the most important for general literary theory.

In his famous Essay,(on Dramatic poesy) Dryden has discussed a number of literary problems, but his main contribution to literary criticism is his further exploration of the principles of imitation and instruction. For Plato the poet’s world being a second-hand imitation of reality was worthless; for Aristotle the poet could achieve a reality more profound than we meet in ordinary experience, by the proper selection and organization of incident; for Sidney, the poet created a world better than the real world, and thereby exerted an ennobling influence on his readers.

None of these critics suggested that there is still another way in which a poet can deal with life, and that is to present it as it is. It was Dryden who made this obvious statement that a play or literature in general is “a just” or thoughtful image of human life. “a just and lively image of human nature, representing the passions and humors, and the changes of fortune to which it is subject, for the delight and instruction of making”. His achievement as a critic is, no doubt, considerable; and despite his lack of system, his inconsistencies and digressions, he has something substantial to offer to his own and later ages.

He make an effective us of the psychological, comparative and historical methods in forming literary judgments. He was the first to point out the facts that time was the final test of literary values, and also to illustrate this doctrine by revealing fresh “beauties” as three of the greatest English poets – Chaucer, Spenser and Shakespeare. Though the was influenced by the critical doctrines of the ancients, yet he assimilated only those influences which found a response in his own nature and temperament.

The secret of Dryden’s greatness as a critic lay in his native sensibility which made him keenly aware of artistic values, and helped him arrive at a dispassionate psychological analysis of those values. His judgment of Shakespeare and Chaucer was based on his own instructive reaction submitted to the test of Nature or reason, rather then on formal rules. It resulted from an imaginative sympathy and not merely from intellect. His criticism of literature was synthetic rather than analytical, and therefore he could view the effects observed with a critical insight which was akin to the creative vision.

It helped him penetrate to the heart of things and find meaning and coherence in the multiplicity of those effects. Pope as a Critic: Pope’s major work was a series of four “Moral Essays” and a work which had nothing to do with satire, the Essay on Man. this last work deals mainly with the place of humankind with respect to the Creator, to his place in Creation, and his happiness. Some of the sentiments (notably those at the beginning of Epistle II) have justly become axiomatic: The Essay on Man was to have formed part of a series of philosophic poems on a systematic plan.

The other pieces were to treat of human reason, of the use of learning, wit, education and riches, of civil and ecclesiastical polity, of the character of women Popes next publication was the Essay on Criticism, written two years earlier, and printed without the author’s name. In every work regard the writers end is one of its sensible precepts, and one that is often neglected by critics of the essay, who comment upon it as if Popes end had been to produce an original and profound treatise on first principles.

His Essay on Criticism established Pope as a significant poetic voice. It also prompted the first of many printed, personal attacks. John Dennis, a prominent critic whom Pope ridiculed in the Essay, aimed his venomous response at Pope’s ailing body, his character, and his religious faith. Joseph Addison, on the other hand, praised Pope for both insight and execution, and Samuel Johnson later hailed the poem for exhibiting “every mode of excellence that can embellish or dignify didactic composition” (Life of Pope).

Windsor-Forest, The Rape of the Lock, and The Temple of Fame followed and confirmed Pope’s place among celebrated poets, a place marked again by the publication of The Works of Mr. Alexander Pope. Pope was only 29. The poetic essay was a relatively new genre, and the “Essay” itself was Pope’s most ambitious work to that time. It was in part an attempt on Pope’s part to identify and refine his own positions as poet and critic, and his response to an ongoing critical debate which centered on the question of whether poetry should be “natural” or written according to predetermined “artificial” rules inherited from the classical past.

His aim was simply to condense, methodize, and give as perfect and novel expression as he could to floating opinions about the poet’s aims and methods, and the critics duties, to what oft was thought, but near so well expressed . The town was interested in belle’s letters, and given to conversing on the subject; Popes essay was simply a brilliant contribution to the fashionable conversation Dr. Samuel Johnson: Samuel was such a dominant literary figure in the second half of the eighteenth century that the period has sometimes been called the Age of Johnson, lived most of his adult life in London.

Until the crown granted him a pension in 1763, he had to support himself by his literary activity, including major projects such as the Dictionary of the English Language (1755) and his edition of the plays of Shakespeare (1765), as well as periodical essay series such as the Rambler (1750-52) and the Idler (1758-60), other separate publications such as the poem The Vanity of Human Wishes (1749) and the tale Rasselas (1759), and miscellaneous writing, mainly for a variety of periodicals. His last major literary project was the series Lives of the Poets (1779-81). whose still living writings are always ignored, a great honest man who will remain forever a figure of half fun because of the leechlike adoration of the greatest and most ridiculous of all biographers. For it is impossible not to believe that, without Boswell, Johnson for us today would shine like a sun in the heavens whilst Addison sat forgotten in coffee houses. ” (from The March of Literature, 1938) – Although best remembered as the compiler of the first comprehensive English dictionary, Dr. Johnson was more than a scholar.

Born at Lichfield and educated at Lichfield Grammar School and Pembroke College, Oxford, he moved to London in 1737 with his wife, Tetty, who was twenty years his senior, and began to earn a living as a journalist and critic, whilst working on plays, poetry and biographies. Johnson began A Dictionary of the English Language in 1747, but did not complete it until 1755. It made his name, but not his fortune. Another of his major works, the satire Rasselas (1759), was written specifically to raise money to pay for his mother’s funeral.

Johnson was at the centre of a literary circle which included such figures as Oliver Goldsmith, Edmund Burke and David Garrick. . Essays on his main works are complemented by thematic discussion of his views on the experience of women in the eighteenth century, politics, imperialism, religion, and travel as well as by chapters covering his life, conversation, letters, and critical reception. Useful reference features include a chronology and guide to further reading.

The keynote to the volume is the seamlessness of Johnson’s life and writing, and the extraordinary humane intelligence he brought to all his activities. Accessibly written by a distinguished group of international scholars, this volume supplies a stimulating range of approaches, making Johnson newly relevant for our time. Despite the consistency of his critical principles, Johnson’s criticism is also very sensitive to the special circumstances of its origin. He unashamedly wrote to earn money.

The form in which he wrote were those demanded by the occasion, and what he wrote was adapted to what was appropriate for that form. Johnson was willing to recalculate work already on hand, and sometimes this work may seem out of place in its new setting; but when composing he was keenly sensitive to what was appropriate to his present occasion. A reader approaching Johnson’s criticism needs to cultivate an understanding of the demands set by each kind of piece that he wrote–prefaces, dedications, lives, notes, reviews, and separate essays.

The reader also needs, if possible, to develop some sense of the context of literary discussion Johnson is joining, for although the particular topics he treats may be largely determined by this context, he is often much less explicit than a modern scholar would be about providing references to orient his reader in the controversy. His Shakespeare criticism provides a good example of most of these observations.

While we are liable to find anywhere in it those gnomic statements that grow out of a full knowledge of literature and life, without a proper sense of the whole piece in which they occur we will not have a true idea of the weight Johnson intended them to have. Chronology of the writers of the age: Following is the list of the prominent writers of the age and their major works. 1. Daniel Defoe(1660-1731) for Robinson Crusoe 2. John Arbuthnot(1667-1735) for History of John Bull 1712 3. Jonathan Swift(1667-1745) for Gulliver’s Travels , A Tale of Tub . Addison(1672-1719) for the Spectator 5. Steele(1672-1729) for The Tatler 6. Alexander Pope(1688-1744) for Dunciad, Rape of The Lock 7. Dr. Johnson(1709-1784) for Preface to Shakespeare, Lives of the Poets 8. Oliver Gold Smith(1730-1774) for The Citizen of The World 9. Charles Churchill(1731-1864) 10. Edmund Burke(1729-1797) Main Novelist of Eighteenth Century: 1. Richardson(1689-1761) for Pamela 2. Fielding(1707-54) for Joseph Andrews 3. Smollett(1721-71) for Roderick Random 4. Sterne(1713_68) for Tristram Shandy

Questions 1. What is the goal of science?

The major goal of science is to ask & answer questions about the physical universe that we live in. How is observation different from imagination? Observation gathers only what data is obviously true. Imagination can go anywhere—factual or not. Write an equation in words & then in symbols for the following sentence: The price of coffee beans is equal to the weight of the beans times the price of the beans per pound. Cost of Beans (C) = Weight of Beans (Wb) x Cost per pound (Cp) (C) = (Wb) x (Cp) . Write an equation in words & then in symbols for the following sentence: The change in the number of individuals in a population is equal to the difference between the number of births & deaths. Let: N = The change in the number of individuals in a population given length of time B = The number of births over a given length of time D = The number of deaths over a given length of time Equation: N = B – D. Describe the steps of the scientific method.

Acquire Data

• Collect data
• Make observations
• Experimentation (where, what, when_ b. Develop a Model (i. e. form a hypothesis)
• Modify, Explain, Expand, & Interpret this Hypothesis

Test the Model

Be prepared to modify the hypothesis or reject it entirely

By what criteria might you determine whether a question might be answered suing the scientific method? Determine if an experiment can be set up to factually assess the question. If it appeals to the human belief, emotions, or feelings, then it is not scientifically testable.

Describe the difference between basic & applied research. Basic Research: the simple quest for knowledge & answers to questions, for no particular reason other than to find out how things work and to advance knowledge. a. t is unencumbered research; it has no agenda b. it has no mission other than to seek new knowledge & information Applied Research: This is research with a mission. Research that starts off with a particular goal, & strives to develop methods to reach that goal.

Discussion Questions 1. Which of the following statements could be tested scientifically to determine whether it is true or false?

Women are shorter than men. This can be scientifically tested b. Most of the Sun’s energy is in the form of heat energy. This can be scientifically tested c. Unicorns are now extinct. This can NOT be scientifically tested d.

Beethoven wrote beautiful music. This can NOT be scientifically tested e. Earth was created over 4 billion years ago. This can be scientifically tested f. Earth was created in a miraculous event. This can NOT be scientifically tested g. Diamond is harder than steel. This can be scientifically tested h. Baseball is a better sport than football viii. This can NOT be scientifically tested i. God exists. This can NOT be scientifically tested j. Vanilla ice cream tastes better than chocolate pudding. This can NOT be scientifically tested k. Men are better scientists than women. This can NOT be scientifically tested . Categorize the following examples as basic research or applied research. The discovery of a new species of bird.

• Basic m. The development of a more fuel-efficient vehicle.
• Applied n. The breeding of a new variety of disease-resistant wheat.
• Applied o. A study of the ecological role of grizzly bears in Yellowstone National Park
• Basic p. The identification of a new chemical compound
• Basic q. The development of a new drug for cancer or AIDS patients
• Applied r. The improvement of wind turbines for energy production.

CHAPTER 2

Review Questions 1. With what ancient science is Stonehenge associated? Stonehenge functioned as a calendar by marking the seasons of the year & certain astronomical events (such as equinox &/or solstice). It did so by aligning stones around a central observation post so that they would align with astronomical events. Midsummer morning sunrise is aligned with the “Heel Stone. ” There are repetitive patterns in the astronomical movements of the sky. By carefully studying these movements, and marking them with sighting stones, the ancients could predict when certain events would reoccur.

Why was the Ptolemaic system accepted as an explanation of celestial motion for over a thousand years? What did it explain? What system challenged the idea that Earth was the center of the universe? The Ptolemaic system explained the apparent observations of movement in the sun, moon, and planets. It also fit into the religious doctrine of the time that believed that earth was the center of the universe and all creation. What were Tyco Brahe’s principal contributions to science? How did he try to resolve the question of the structure of the universe? Tyco Brahe constructed large brass tools for astronomical measurements.

These tools were built as accurately as possible. He even took into accound the expansion and contraction of the brass due to changes in temperature. He was able to make measurements with an accuracy of 2 min. of arc [quite good for the time]. In his time the telescope had not been invented. All observation was with the naked eye. Tyco gathered 25 years of extremely accurate data. What was Kepler’s role in interpreting Tyco Brahe’s data? Kepler was a brilliant mathematician. He had access to a large amount (25 years) of the most accurate astronomical measurement available to mankind (the data of Tyco Brahe).

It was Kepler that first demonstrated that the orbits of the planets around the sun were elliptical and not circular. Also, from this data came Kepler’s Laws of Planetary Motion. How did Galileo apply the scientific method to his study of falling objects? Galileo is especially known for his work in experimental techniques. He studied falling objects by doing repetitive experiments and making careful measurements. He is most famous for his work of bodies moving down an inclined plane. After his observations he would try to define his observations mathematically. Then he would test the hypothesis further by experimentation. . According to Newton, what are the 2 kinds of motion in the universe? How did this view differ from those of previous scholars? Newton described uniform motion & accelerated motion. Previous to Newton, scientists thought that moving bodies (i. e. planets) moved in circles & would continue moving in circles if left alone. Thus, for an object to move in a circle some outside force must be affecting it. Newton showed that there was Uniform Motion of an object traveling in a straight line at a constant speed. There was also Accelerated Motion which involves objects changing speed, direction, or both.

What is the difference between the constants g & G? g = the acceleration of gravity on earth. 8m/s2 G = Newton’s Universal Gravitational Constant 6. 67 x 10 -11 N-m2/kg2 8. What is the difference between weight & mass? Mass is the fixed amount of matter in an object. It never changes. (kilograms) Weight is the force by which gravity attracts the mass (Newtons & pounds)

Discussion Questions

Can you give an everyday example that illustrates the difference between acceleration & velocity? Which, if any, of the following objects does not exert a gravitational force on you?

1. This book
2. The Sun
3. The nearest star
4. A distant galaxy

The Atlantic Ocean

They all exert a gravitational force on you. Why don’t the planets just fly off into space? What keeps them in their orbits? The gravitational force of the Sun holds the planets in orbit, just as the gravitational force of the earth holds our moon in orbit. Why are observatories built as far away from major cities as possible? Observatories are built away from cities to avoid interference from city lights. What forces keep a pendulum swinging back and forth? Mechanical Energy is swapping both kinetic energy & potential energy back & forth.

Problems

If a person weighs 150 lbs, what does he weigh in Newtons? A person weighing 150 pounds would be equivalent to 667. 4 newtons 0. 454 kg/lb x 150 lb x 9. 8 newtons/kg = 667. 4 newtons Or 150 lb x 4. 43 newtons/lb = 664. 5 newtons 2. If your car goes from 0 to 60 mph in 6 seconds, what is your acceleration? If you step on the brake and your car goes from 60 mph to 0 in 3 seconds, what is your acceleration? Convert everything to Meters per second: [60 miles/hour x 1. 61 km/mile x 1000 m/km] divided by 3600 sec/hour Thus 60 mph = 26. 83 meters/sec This is Vfinal = 26. 83 m/sec V initial = zero cceleration = Vfinal – V initial 6 sec a = 26. 83 m/sec – 0 m/sec 4. 47 meters/sec/sec acceleration 6 sec Brake deceleration: a = 26. 83 = 8. 94 meters/sec/sec deceleration

Chapter 3 Review

Questions #1: What is the scientific definition of work? How does it differ from ordinary English use? Work is a force that operates over a distance. In common language, work can be done without moving something.

In science, something has to move. #2: What is a joule? What is the English system of units equivalent of a joule?

The joule is the amount of work done when a force of 1 Newton operates through a distance of 1 meter. Or, it is the amount of energy necessary to do 1 joule of work.

The English equivalent is the foot-pound. #3: What is the difference between energy and power? What is a unit of power?

How does speed relate to power? Energy is the potential to do work. Power is the rate at which work is the rate at which work is done. The watt is a metric measure of power. It is the speed at which work is done. It is 1 joule per second.

The horsepower also measures power. 1 horsepower is 550 foot-Pounds per second. #7: What does it mean to say that different forms of energy are interchangeable? Energy cannot be created or destroyed but it can be converted to one form or another. Examples: (1) The chemical energy of gasoline is converted to heat energy and mechanical kinetic energy in your automobile. (2) The sun’s radiant energy is converted to electricity by a solar cell, which can run a small motor, thus converting the electrical energy to mechanical energy, etc. , #10: Does the total amount of energy in an isolated system change over tie? Why or why not?

There is a finite and constant amount of energy in the universe. In any closed system experiment the total amount of energy never changes. It may be converted to different forms, but like an accountant’s ledger, it can all be accounted for. Problems #2: Which has more gravitational potential energy: a 200-kilogram boulder 1 meter off the ground a 50-kilogram boulder 4 meters off the ground, or a 1-kilogram rock 200 meters off the ground? Which of these can do the most work if all the potential energy was converted into kinetic energy? P. E. = mgh P. E. = (200 kg) (9. 8 m/sec2)(1 meter) = 1960 Joules P. E. = (50 kg) (9. m/sec2)(4meters) = 1960 Joules P. E. = ( 1 kg) (9. 8 m/sec2) (200 meters) = 1960 Joules ALL THE SAME #4: According to Einstein’s famous equation, E = mc2, how much energy would be released if a pound of feathers was converted entirely into energy? A pound of lead? (Convert pounds into kilograms) 1 lb is equivalent to 0. 454 kg on Earth c = speed of light = 299,792,458 m/sec E = mc2 E = (0. 454 kg) (299,792,458 m/sec)2 E = (0. 454 kg) (8. 9876 x 10 16) E = 4. 08 x 10 16 joules. It does not matter what the mass is made of, the energy conversion would be the same.

Chapter 4 Review

Questions #2: What is specific heat capacity? Which heats more quickly, a kilogram of water or a kilogram of copper? Why? It takes longer to heat the Kg of water because it requires more heat energy than the copper. This is shown by the specific heat of water which is 1. 00 and the specific heat of copper which is 0. 092. It requires 1000 calories to raise the kilogram of water by each degree C, while it requires only 92 calories to raise a Kg of copper by each degree. #3: What are the 3 different ways by which heat is transferred? How are these three phenomena occurring while you are reading this book?

Heat can be transferred by: conduction (generally in solids) convection (usually in liquids & gases) radiation (works best in a vacuum #4: What is the difference between temperature & heat? TEMPERATURE is the “intensity” of heat. It actually represents the kinetic energy of the molecules and atoms within the substance. It is measured in degrees. HEAT is the true measure of thermal energy. It is measured in calories. #6: Is there a directionality to the flow of heat? Yes. Heat can only from higher temperatures toward lower temperatures #8: Describe three common temperature scales. What fixed points are use to calibrate them?

The three common temperature scales are Fahrenheit, Celsius, & Kelvin. Fahrenheit: Based approximately on the living conditions on the surface of the planet. It approximates a temperature range between the coldest days & the hottest days which is 0 def. F to 1000 deg. F. Water freezes at 32 deg F & boils at 212 deg F Celsius: based on the properties of water. 0 deg C is the freezing point of water & 100 deg C is the boiling point. (at 1 atmosphere of pressure (i. e. sea level) Kelvin: the absolute energy scale. 0 deg Kelvin is the point where no thermal energy exists at all (we have never achieved this in a lab)

In the Kelvin scale water freezes at 273 deg K & boils at 373 deg K #11: What is entropy? Give an example of a situation in which entropy increases. Can the entropy of an isolated system decrease? If so, how? Entropy: a measure of disorder in a system * Natural systems, left to their own devices will tend to increase in entropy (i. e. becomes more disordered) * Example of decreasing entropy is found in the formation of ice cubes from water in your freezer; the extraction of salt from seawater, the mining and smelting of gold from the earths crust. But notice that we have to expend energy in all of these examples.

Erosion in Earth is mainly caused by water or moisture, wind, and other earthly activities. However, in other planets like Mercury and Venus, as well as our own satellite, which is the Moon, there is less erosion activity. Considering their distance from the Sun, the two mentioned planets are the closest ones to the Sun, and in case of Moon, it has the same distance as the Earth from the Sun which is 1 astronomical unit. We could say that in these heavenly bodies, the moisture is least to exist since they are prone to the intense heat of the Sun, considering that the Moon gets its light from the Sun.

Aside from that, the Sun has strong gravity that enables it self to pull the planets and other heavenly bodies in the Solar System. Considering that the Mercury and Venus are the planets considered closest to the sun, both planets have received also the strongest attraction of the gravitational pull. In this case, the materials of the planets are more intact that could prevent to be eroded.

In relation to the planetary size, it is correlated to the gravity such that the bigger the planet or the heavenly body, the greater of its gravitational pull. The Mercury, Venus, and Moon, which are relatively small bodies in Solar System, it has lesser gravity pull than the Earth. However, with the influence of the Earth’s gravity to the Moon, it prevents the moon from its orbiting and other erosional activity in the said satellite. Mercury and Venus, as it was mentioned before, both planets have been affected by the gravitational force of the Sun. The fallen heavenly bodies, such as meteor and asteroids, that also causes erosion in planets would be avoided by attraction of gravity pull of the Sun. Instead of collision with Mercury or Venus, it would be then collided with the Sun. In this case, there would be lesser erosional activity.

Reference:

July 1, 2007

July 1, 2007

Presents NCERT Text Books NCERT Text Books: 11th Class Physics About Us: Prep4Civils, website is a part of Sukratu Innovations, a start up by IITians. The main theme of the company is to develop new web services which will help people. P rep4Civils is an online social networking platform intended for the welfare of people who are preparing for Civil services examinations. The whole website was built on open-source platform Wordpress. Contact Details: Website: http://www. prep4civils. com/ Email: admin@prep4civils. com

Disclaimer and Terms of Use: By following Creative Common License, for the welfare of large student body we are merging all the PDF files provided by NCERT website and redistributing the files by giving proper credit to NCERT website and the redistribution is based on the norms of Creative Common License. We are not commercially distributing the files. People who are downloading these files should not be engaged in any sort of sales or commercial distribution of these files. They can redistribute these copies freely by giving proper credit to the original author, NCERT (http://www. ncert. nic. in/NCERTS/textbook/textbook. tm) and “Prep4Civils” (http://www. prep4civils. com/) by providing proper hyperlinks of the websites. Any sort of cliches can be addressed at admin@prep4civils. com and proper action will be taken. CONTENTS FOREWORD PREFACE A NOTE FOR THE TEACHER CHAPTER iii v x 1 PHYSICAL WORLD 1. 1 1. 2 1. 3 1. 4 1. 5 What is physics ? Scope and excitement of physics Physics, technology and society Fundamental forces in nature Nature of physical laws CHAPTER 1 2 5 6 10 2 UNITS AND MEASUREMENTS 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 2. 10 Introduction The international system of units Measurement of length Measurement of mass

Measurement of time Accuracy, precision of instruments and errors in measurement Significant figures Dimensions of physical quantities Dimensional formulae and dimensional equations Dimensional analysis and its applications CHAPTER 16 16 18 21 22 22 27 31 31 32 3 MOTION IN A STRAIGHT LINE 3. 1 3. 2 3. 3 3. 4 3. 5 3. 6 3. 7 Introduction Position, path length and displacement Average velocity and average speed Instantaneous velocity and speed Acceleration Kinematic equations for uniformly accelerated motion Relative velocity CHAPTER 39 39 42 43 45 47 51 4 MOTION IN A PLANE 4. 1 4. 2 4. 3 4. 4 4. 5 Introduction

Scalars and vectors Multiplication of vectors by real numbers Addition and subtraction of vectors – graphical method Resolution of vectors 65 65 67 67 69 CK xii 4. 6 4. 7 4. 8 4. 9 4. 10 4. 11 Vector addition – analytical method Motion in a plane Motion in a plane with constant acceleration Relative velocity in two dimensions Projectile motion Uniform circular motion CHAPTER 71 72 75 76 77 79 5 LAWS OF MOTION 5. 1 5. 2 5. 3 5. 4 5. 5 5. 6 5. 7 5. 8 5. 9 5. 10 5. 11 Introduction Aristotle’s fallacy The law of inertia Newton’s first law of motion Newton’s second law of motion Newton’s third law of motion Conservation of momentum

Equilibrium of a particle Common forces in mechanics Circular motion Solving problems in mechanics CHAPTER 89 90 90 91 93 96 98 99 100 104 105 6 WORK, ENERGY AND POWER 6. 1 6. 2 6. 3 6. 4 6. 5 6. 6 6. 7 6. 8 6. 9 6. 10 6. 11 6. 12 Introduction Notions of work and kinetic energy : The work-energy theorem Work Kinetic energy Work done by a variable force The work-energy theorem for a variable force The concept of potential energy The conservation of mechanical energy The potential energy of a spring Various forms of energy : the law of conservation of energy Power Collisions CHAPTER 114 116 116 117 118 119 120 121 123 126 28 129 7 SYSTEM OF PARTICLES AND ROTATIONAL MOTION 7. 1 7. 2 7. 3 7. 4 7. 5 7. 6 7. 7 7. 8 7. 9 7. 10 Introduction Centre of mass Motion of centre of mass Linear momentum of a system of particles Vector product of two vectors Angular velocity and its relation with linear velocity Torque and angular momentum Equilibrium of a rigid body Moment of inertia Theorems of perpendicular and parallel axes 141 144 148 149 150 152 154 158 163 164 CK xiii 7. 11 7. 12 7. 13 7. 14 Kinematics of rotational motion about a fixed axis Dynamics of rotational motion about a fixed axis Angular momentum in case of rotations about a fixed axis

Rolling motion CHAPTER 167 169 171 173 8 GRAVITATION 8. 1 8. 2 8. 3 8. 4 8. 5 8. 6 8. 7 8. 8 8. 9 8. 10 8. 11 8. 12 Introduction Kepler’s laws Universal law of gravitation The gravitational constant Acceleration due to gravity of the earth Acceleration due to gravity below and above the surface of earth Gravitational potential energy Escape speed Earth satellite Energy of an orbiting satellite Geostationary and polar satellites Weightlessness 183 184 185 189 189 190 191 193 194 195 196 197 APPENDICES 203 ANSWERS 219 CK CK CONTENTS FOREWORD PREFACE A NOTE FOR THE TEACHERS CHAPTER iii vii x 9 MECHANICAL PROPERTIES OF SOLIDS 9. 9. 2 9. 3 9. 4 9. 5 9. 6 9. 7 Introduction Elastic behaviour of solids Stress and strain Hooke’s law Stress-strain curve Elastic moduli Applications of elastic behaviour of materials CHAPTER 231 232 232 234 234 235 240 10 MECHANICAL PROPERTIES OF FLUIDS 10. 1 10. 2 10. 3 10. 4 10. 5 10. 6 10. 7 Introduction Pressure Streamline flow Bernoulli’s principle Viscosity Reynolds number Surface tension CHAPTER 246 246 253 254 258 260 261 11 THERMAL PROPERTIES OF MATTER 11. 1 11. 2 11. 3 11. 4 11. 5 11. 6 11. 7 11. 8 11. 9 11. 10 Introduction Temperature and heat Measurement of temperature Ideal-gas equation and absolute temperature

Thermal expansion Specific heat capacity Calorimetry Change of state Heat transfer Newton’s law of cooling CHAPTER 274 274 275 275 276 280 281 282 286 290 12 THERMODYNAMICS 12. 1 12. 2 Introduction Thermal equilibrium 298 299 CK CK xii 12. 3 12. 4 12. 5 12. 6 12. 7 12. 8 12. 9 12. 10 12. 11 12. 12 12. 13 Zeroth law of thermodynamics Heat, internal energy and work First law of thermodynamics Specific heat capacity Thermodynamic state variables and equation of state Thermodynamic processes Heat engines Refrigerators and heat pumps Second law of thermodynamics Reversible and irreversible processes Carnot engine CHAPTER 300 300 302 03 304 305 308 308 309 310 311 13 KINETIC THEORY 13. 1 13. 2 13. 3 13. 4 13. 5 13. 6 13. 7 Introduction Molecular nature of matter Behaviour of gases Kinetic theory of an ideal gas Law of equipartition of energy Specific heat capacity Mean free path CHAPTER 318 318 320 323 327 328 330 14 OSCILLATIONS 14. 1 14. 2 14. 3 14. 4 14. 5 14. 6 14. 7 14. 8 14. 9 14. 10 Introduction Periodic and oscilatory motions Simple harmonic motion Simple harmonic motion and uniform circular motion Velocity and acceleration in simple harmonic motion Force law for simple harmonic motion Energy in simple harmonic motion Some systems executing SHM

Damped simple harmonic motion Forced oscillations and resonance CHAPTER 336 337 339 341 343 345 346 347 351 353 15 WAVES 15. 1 15. 2 15. 3 15. 4 15. 5 15. 6 Introduction Transverse and longitudinal waves Displacement relation in a progressive wave The speed of a travelling wave The principle of superposition of waves Reflection of waves 363 365 367 369 373 374 CK CK xiii 15. 7 15. 8 Beats Doppler effect 379 381 ANSWERS 391 BIBLIOGRAPHY 401 INDEX 403 CK CHAPTER ONE PHYSICAL WORLD 1. 1 WHAT IS PHYSICS ? 1. 1 What is physics ? 1. 2 Scope and excitement of physics 1. 3 Physics, technology and society 1. 4 Fundamental forces in nature 1. Nature of physical laws Summary Exercises Humans have always been curious about the world around them. The night sky with its bright celestial objects has fascinated humans since time immemorial. The regular repetitions of the day and night, the annual cycle of seasons, the eclipses, the tides, the volcanoes, the rainbow have always been a source of wonder. The world has an astonishing variety of materials and a bewildering diversity of life and behaviour. The inquiring and imaginative human mind has responded to the wonder and awe of nature in different ways. One kind of response from the earliest times has been to observe the hysical environment carefully, look for any meaningful patterns and relations in natural phenomena, and build and use new tools to interact with nature. This human endeavour led, in course of time, to modern science and technology. The word Science originates from the Latin verb Scientia meaning ‘to know’. The Sanskrit word Vijnan and the Arabic word Ilm c onvey similar meaning, namely ‘knowledge’. Science, in a broad sense, is as old as human species. The early civilisations of Egypt, India, China, Greece, Mesopotamia and many others made vital contributions to its progress. From the sixteenth century onwards, great strides were made n science in Europe. By the middle of the twentieth century, science had become a truly international enterprise, with many cultures and countries contributing to its rapid growth. What is Science and what is the so-called Scientific Method ? Science is a systematic attempt to understand natural phenomena in as much detail and depth as possible, and use the knowledge so gained to predict, modify and control phenomena. Science is exploring, experimenting and predicting from what we see around us. The curiosity to learn about the world, unravelling the secrets of nature is the first step towards the discovery of science.

The scientific method involves several interconnected steps : Systematic observations, controlled experiments, qualitative and 2 quantitative reasoning, mathematical modelling, prediction and verification or falsification of theories. Speculation and conjecture also have a place in science; but ultimately, a scientific theory, to be acceptable, must be verified by relevant observations or experiments. There is much philosophical debate about the nature and method of science that we need not discuss here. The interplay of theory and observation (or experiment) is basic to the progress of science. Science is ever dynamic.

There is no ‘final’ theory in science and no unquestioned authority among scientists. As observations improve in detail and precision or experiments yield new results, theories must account for them, if necessary, by introducing modifications. Sometimes the modifications may not be drastic and may lie within the framework of existing theory. For example, when Johannes Kepler (1571-1630) examined the extensive data on planetary motion collected by Tycho Brahe (1546-1601), the planetary circular orbits in heliocentric theory (sun at the centre of the solar system) imagined by Nicolas Copernicus (1473–1543) had to be replaced by elliptical rbits to fit the data better. Occasionally, however, the existing theory is simply unable to explain new observations. This causes a major upheaval in science. In the beginning of the twentieth century, it was realised that Newtonian mechanics, till then a very successful theory, could not explain some of the most basic features of atomic phenomena. Similarly, the then accepted wave picture of light failed to explain the photoelectric effect properly. This led to the development of a radically new theory (Quantum Mechanics) to deal with atomic and molecular phenomena. Just as a new experiment may suggest an lternative theoretical model, a theoretical advance may suggest what to look for in some experiments. The result of experiment of scattering of alpha particles by gold foil, in 1911 by Ernest Rutherford (1871–1937) established the nuclear model of the atom, which then became the basis of the quantum theory of hydrogen atom given in 1913 by Niels Bohr (1885–1962). On the other hand, the concept of antiparticle was first introduced theoretically by Paul Dirac (1902–1984) in 1930 and confirmed two years later by the experimental discovery of positron (antielectron) by Carl Anderson. P HYSICS Physics is a basic discipline in the category f Natural Sciences, which also includes other disciplines like Chemistry and Biology. The word Physics comes from a Greek word meaning nature. Its Sanskrit equivalent is Bhautiki that is used to refer to the study of the physical world. A precise definition of this discipline is neither possible nor necessary. We can broadly describe physics as a study of the basic laws of nature and their manifestation in different natural phenomena. The scope of physics is described briefly in the next section. Here we remark on two principal thrusts in physics : unification and reduction. In Physics, we attempt to explain diverse hysical phenomena in terms of a few concepts and laws. The effort is to see the physical world as manifestation of some universal laws in different domains and conditions. For example, the same law of gravitation (given by Newton) describes the fall of an apple to the ground, the motion of the moon around the earth and the motion of planets around the sun. Similarly, the basic laws of electromagnetism (Maxwell’s equations) govern all electric and magnetic phenomena. The attempts to unify fundamental forces of nature (section 1. 4) reflect this same quest for unification. A related effort is to derive the properties of a igger, more complex, system from the properties and interactions of its constituent simpler parts. This approach is called reductionism and is at the heart of physics. For example, the subject of thermodynamics, developed in the nineteenth century, deals with bulk systems in terms of macroscopic quantities such as temperature, internal energy, entropy, etc. Subsequently, the subjects of kinetic theory and statistical mechanics interpreted these quantities in terms of the properties of the molecular constituents of the bulk system. In particular, the temperature was seen to be related to the average kinetic energy of molecules of the system. . 2 SCOPE AND EXCITEMENT OF PHYSICS We can get some idea of the scope of physics by looking at its various sub-disciplines. Basically, there are two domains of interest : macroscopic and microscopic. The macroscopic domain includes phenomena at the laboratory, terrestrial and astronomical scales. The microscopic domain includes atomic, molecular and nuclear P HYSICAL WORLD phenomena*. Classical Physics deals mainly with macroscopic phenomena and includes subjects like Mechanics, Electrodynamics, Optics a nd T hermodynamics . Mechanics founded on Newton’s laws of motion and the law of gravitation is concerned with the motion (or quilibrium) of particles, rigid and deformable bodies, and general systems of particles. The propulsion of a rocket by a jet of ejecting gases, propagation of water waves or sound waves in air, the equilibrium of a bent rod under a load, etc. , are problems of mechanics. Electrodynamics deals with electric and magnetic phenomena associated with charged and magnetic bodies. Its basic laws were given by Coulomb, Oersted, Fig. 1. 1 chemical process, etc. , are problems of interest in thermodynamics. The microscopic domain of physics deals with the constitution and structure of matter at the minute scales of atoms and nuclei (and even ower scales of length) and their interaction with different probes such as electrons, photons and other elementary particles. Classical physics is inadequate to handle this domain and Quantum Theory is currently accepted as the proper framework for explaining microscopic phenomena. Overall, the edifice of physics is beautiful and imposing and you will appreciate it more as you pursue the subject. Theory and experiment go hand in hand in physics and help each other’s progress. The alpha scattering experiments of Rutherford gave the nuclear model of the atom. Ampere and Faraday, and encapsulated by Maxwell in his famous set of equations.

The motion of a current-carrying conductor in a magnetic field, the response of a circuit to an ac voltage (signal), the working of an antenna, the propagation of radio waves in the ionosphere, etc. , are problems of electrodynamics. Optics deals with the phenomena involving light. The working of telescopes and microscopes, colours exhibited by thin films, etc. , are topics in optics. Thermodynamics, in contrast to mechanics, does not deal with the motion of bodies as a whole. Rather, it deals with systems in macroscopic equilibrium and is concerned with changes in internal energy, temperature, entropy, etc. , of the ystem through external work and transfer of heat. The efficiency of heat engines and refrigerators, the direction of a physical or * 3 You can now see that the scope of physics is truly vast. It covers a tremendous range of magnitude of physical quantities like length, mass, time, energy, etc. At one end, it studies phenomena at the very small scale of length -14 (10 m or even less) involving electrons, protons, etc. ; at the other end, it deals with astronomical phenomena at the scale of galaxies or even the entire universe whose extent is of the order of 26 10 m. The two length scales differ by a factor of 40 10 or even more.

The range of time scales can be obtained by dividing the length scales by the –22 speed of light : 10 s to 1018 s. The range of masses goes from, say, 10–30 kg (mass of an 55 electron) to 10 kg (mass of known observable universe). Terrestrial phenomena lie somewhere in the middle of this range. Recently, the domain intermediate between the macroscopic and the microscopic (the so-called mesoscopic physics), dealing with a few tens or hundreds of atoms, has emerged as an exciting field of research. 4 Physics is exciting in many ways. To some people the excitement comes from the elegance and universality of its basic theories, from the fact that few basic concepts and laws can explain phenomena covering a large range of magnitude of physical quantities. To some others, the challenge in carrying out imaginative new experiments to unlock the secrets of nature, to verify or refute theories, is thrilling. Applied physics is equally demanding. Application and exploitation of physical laws to make useful devices is the most interesting and exciting part and requires great ingenuity and persistence of effort. What lies behind the phenomenal progress of physics in the last few centuries? Great progress usually accompanies changes in our basic perceptions.

First, it was realised that for scientific progress, only qualitative thinking, though no doubt important, is not enough. Quantitative measurement is central to the growth of science, especially physics, because the laws of nature happen to be expressible in precise mathematical equations. The second most important insight was that the basic laws of physics are universal — the same laws apply in widely different contexts. Lastly, the strategy of approximation turned out to be very successful. Most observed phenomena in daily life are rather complicated manifestations of the basic laws. Scientists recognised the importance f extracting the essential features of a phenomenon from its less significant aspects. It is not practical to take into account all the complexities of a phenomenon in one go. A good strategy is to focus first on the essential features, discover the basic principles and then introduce corrections to build a more refined theory of the phenomenon. For example, a stone and a feather dropped from the same height do not reach the ground at the same time. The reason is that the essential aspect of the phenomenon, namely free fall under gravity, is complicated by the presence of air resistance. To get the law of free all under gravity, it is better to create a situation wherein the air resistance is negligible. We can, for example, let the stone and the feather fall through a long evacuated tube. In that case, the two objects will fall almost at the same rate, giving the basic law that acceleration due to gravity is independent of the mass of the object. With the basic law thus found, we can go back to the feather, introduce corrections due to air resistance, modify the existing theory and try to build a more realistic P HYSICS Hypothesis, axioms and models One should not think that everything can be proved with physics and mathematics.

All physics, and also mathematics, is based on assumptions, each of which is variously called a hypothesis or axiom or postulate, etc. For example, the universal law of gravitation proposed by Newton is an assumption or hypothesis, which he proposed out of his ingenuity. Before him, there were several observations, experiments and data, on the motion of planets around the sun, motion of the moon around the earth, pendulums, bodies falling towards the earth etc. Each of these required a separate explanation, which was more or less qualitative. What the universal law of gravitation says is that, if we assume that any two odies in the universe attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them, then we can explain all these observations in one stroke. It not only explains these phenomena, it also allows us to predict the results of future experiments. A hypothesis is a supposition without assuming that it is true. It would not be fair to ask anybody to prove the universal law of gravitation, because it cannot be proved. It can be verified and substantiated by experiments and observations. An axiom is a self-evident truth while a model s a theory proposed to explain observed phenomena. But you need not worry at this stage about the nuances in using these words. For example, next year you will learn about Bohr’s model of hydrogen atom, in which Bohr assumed that an electron in the hydrogen atom follows certain rules (postutates). Why did he do that? There was a large amount of spectroscopic data before him which no other theory could explain. So Bohr said that if we assume that an atom behaves in such a manner, we can explain all these things at once. Einstein’s special theory of relativity is also based on two postulates, the constancy of the speed f electromagnetic radiation and the validity of physical laws in all inertial frame of reference. It would not be wise to ask somebody to prove that the speed of light in vacuum is constant, independent of the source or observer. In mathematics too, we need axioms and hypotheses at every stage. Euclid’s statement that parallel lines never meet, is a hypothesis. This means that if we assume this statement, we can explain several properties of straight lines and two or three dimensional figures made out of them. But if you don’t assume it, you are free to use a different axiom and get a new geometry, as has indeed happened in he past few centuries and decades. P HYSICAL WORLD 5 theory of objects falling to the earth under gravity. 1. 3 PHYSICS, TECHNOLOGY AND SOCIETY The connection between physics, technology and society can be seen in many examples. The discipline of thermodynamics arose from the need to understand and improve the working of heat engines. The steam engine, as we know, is inseparable from the Industrial Revolution in England in the eighteenth century, which had great impact on the course of human civilisation. Sometimes technology gives rise to new physics; at other times physics generates new technology.

An example of the latter is the wireless communication technology that followed the discovery of the basic laws of electricity and magnetism in the nineteenth century. The applications of physics are not always easy to foresee. As late as 1933, the great physicist Ernest Rutherford had dismissed the possibility of tapping energy from atoms. But only a few years later, in 1938, Hahn and Meitner discovered the phenomenon of neutron-induced fission of uranium, which would serve as the basis of nuclear power reactors and nuclear weapons. Yet another important example of physics giving rise to technology is the silicon chip’ that triggered the computer revolution in the last three decades of the twentieth century. A most significant area to which physics has and will contribute is the development of alternative energy resources. The fossil fuels of the planet are dwindling fast and there is an urgent need to discover new and affordable sources of energy. Considerable progress has already been made in this direction (for example, in conversion of solar energy, geothermal energy, etc. , into electricity), but much more is still to be accomplished. Table1. 1 lists some of the great physicists, their major contribution and the country of rigin. You will appreciate from this table the multi-cultural, international character of the scientific endeavour. Table 1. 2 lists some important technologies and the principles of physics they are based on. Obviously, these tables are not exhaustive. We urge you to try to add many names and items to these tables with the help of your teachers, good books and websites on science. You will find that this exercise is very educative and also great fun. And, assuredly, it will never end. The progress of science is unstoppable! Physics is the study of nature and natural phenomena. Physicists try to discover the rules hat are operating in nature, on the basis of observations, experimentation and analysis. Physics deals with certain basic rules/laws governing the natural world. What is the nature Table 1. 1 Some physicists from different countries of the world and their major contributions Name Major contribution/discovery Country of Origin Archimedes Principle of buoyancy; Principle of the lever Greece Galileo Galilei Law of inertia Italy Christiaan Huygens Wave theory of light Holland Isaac Newton Universal law of gravitation; Laws of motion; Reflecting telescope U. K. Michael Faraday Laws of electromagnetic induction U. K. James Clerk Maxwell

Electromagnetic theory; Light-an electromagnetic wave U. K. Heinrich Rudolf Hertz Generation of electromagnetic waves Germany J. C. Bose Ultra short radio waves India W. K. Roentgen X-rays Germany J. J. Thomson Electron U. K. Marie Sklodowska Curie Discovery of radium and polonium; Studies on Poland natural radioactivity Albert Einstein Explanation of photoelectric effect; Theory of relativity Germany 6 P HYSICS Name Major contribution/discovery Country of Origin Victor Francis Hess Cosmic radiation Austria R. A. Millikan Measurement of electronic charge U. S. A. Ernest Rutherford Nuclear model of atom New Zealand Niels Bohr

Quantum model of hydrogen atom Denmark C. V. Raman Inelastic scattering of light by molecules India Louis Victor de Borglie Wave nature of matter France M. N. Saha Thermal ionisation India S. N. Bose Quantum statistics India Wolfgang Pauli Exclusion principle Austria Enrico Fermi Controlled nuclear fission Italy Werner Heisenberg Quantum mechanics; Uncertainty principle Germany Paul Dirac Relativistic theory of electron; Quantum statistics U. K. Edwin Hubble Expanding universe U. S. A. Ernest Orlando Lawrence Cyclotron U. S. A. James Chadwick Neutron U. K. Hideki Yukawa Theory of nuclear forces Japan Homi Jehangir Bhabha

Cascade process of cosmic radiation India Lev Davidovich Landau Theory of condensed matter; Liquid helium Russia S. Chandrasekhar Chandrasekhar limit, structure and evolution of stars India John Bardeen Transistors; Theory of super conductivity U. S. A. C. H. Townes Maser; Laser U. S. A. Abdus Salam Unification of weak and electromagnetic interactions Pakistan of physical laws? We shall now discuss the nature of fundamental forces and the laws that govern the diverse phenomena of the physical world. 1. 4 FUNDAMENTAL FORCES IN NATURE* We all have an intuitive notion of force. In our experience, force is needed to push, carry or hrow objects, deform or break them. We also experience the impact of forces on us, like when a moving object hits us or we are in a merry-goround. Going from this intuitive notion to the proper scientific concept of force is not a trivial matter. Early thinkers like Aristotle had wrong * ideas about it. The correct notion of force was arrived at by Isaac Newton in his famous laws of motion. He also gave an explicit form for the force for gravitational attraction between two bodies. We shall learn these matters in subsequent chapters. In the macroscopic world, besides the gravitational force, we encounter several kinds f forces: muscular force, contact forces between bodies, friction (which is also a contact force parallel to the surfaces in contact), the forces exerted by compressed or elongated springs and taut strings and ropes (tension), the force of buoyancy and viscous force when solids are in Sections 1. 4 and 1. 5 contain several ideas that you may not grasp fully in your first reading. However, we advise you to read them carefully to develop a feel for some basic aspects of physics. These are some of the areas which continue to occupy the physicists today. P HYSICAL WORLD 7 Table 1. 2 Link between technology and physics Technology

Scientific principle(s) Steam engine Laws of thermodynamics Nuclear reactor Controlled nuclear fission Radio and Television Generation, propagation and detection of electromagnetic waves Computers Digital logic Lasers Light amplification by stimulated emission of radiation Production of ultra high magnetic fields Superconductivity Rocket propulsion Newton’s laws of motion Electric generator Faraday’s laws of electromagnetic induction Hydroelectric power Conversion of gravitational potential energy into electrical energy Aeroplane Bernoulli’s principle in fluid dynamics Particle accelerators Motion of charged particles in electromagnetic ields Sonar Reflection of ultrasonic waves Optical fibres Total internal reflection of light Non-reflecting coatings Thin film optical interference Electron microscope Wave nature of electrons Photocell Photoelectric effect Fusion test reactor (Tokamak) Magnetic confinement of plasma Giant Metrewave Radio Telescope (GMRT) Detection of cosmic radio waves Bose-Einstein condensate Trapping and cooling of atoms by laser beams and magnetic fields. contact with fluids, the force due to pressure of a fluid, the force due to surface tension of a liquid, and so on. There are also forces involving charged nd magnetic bodies. In the microscopic domain again, we have electric and magnetic forces, nuclear forces involving protons and neutrons, interatomic and intermolecular forces, etc. We shall get familiar with some of these forces in later parts of this course. A great insight of the twentieth century physics is that these different forces occurring in different contexts actually arise from only a small number of fundamental forces in nature. For example, the elastic spring force arises due to the net attraction/repulsion between the neighbouring atoms of the spring when the spring is elongated/compressed. This net ttraction/repulsion can be traced to the (unbalanced) sum of electric forces between the charged constituents of the atoms. In principle, this means that the laws for ‘derived’ forces (such as spring force, friction) are not independent of the laws of fundamental forces in nature. The origin of these derived forces is, however, very complex. At the present stage of our understanding, we know of four fundamental forces in nature, which are described in brief here : 8 P HYSICS Albert Einstein (1879-1955) Albert Einstein, born in Ulm, Germany in 1879, is universally regarded as one of the greatest physicists of all time.

His astonishing scientific career began with the publication of three path-breaking papers in 1905. In the first paper, he introduced the notion of light quanta (now called photons) and used it to explain the features of photoelectric effect that the classical wave theory of radiation could not account for. In the second paper, he developed a theory of Brownian motion that was confirmed experimentally a few years later and provided a convincing evidence of the atomic picture of matter. The third paper gave birth to the special theory of relativity that made Einstein a legend in his own life time.

In the next decade, he explored the consequences of his new theory which included, among other things, the mass-energy equivalence enshrined in his famous equation E = mc2. He also created the general version of relativity (The General Theory of Relativity), which is the modern theory of gravitation. Some of Einstein’s most significant later contributions are: the notion of stimulated emission introduced in an alternative derivation of Planck’s blackbody radiation law, static model of the universe which started modern cosmology, quantum statistics of a gas of massive bosons, and a critical analysis of the foundations of quantum mechanics.

The year 2005 was declared as International Year of Physics, in recognition of Einstein’s monumental contribution to physics, in year 1905, describing revolutionary scientific ideas that have since influenced all of modern physics. 1. 4. 1 Gravitational Force The gravitational force is the force of mutual attraction between any two objects by virtue of their masses. It is a universal force. Every object experiences this force due to every other object in the universe. All objects on the earth, for example, experience the force of gravity due to the earth. In particular, gravity governs the motion of the moon and artificial satellites around he earth, motion of the earth and planets around the sun, and, of course, the motion of bodies falling to the earth. It plays a key role in the large-scale phenomena of the universe, such as formation and evolution of stars, galaxies and galactic clusters. 1. 4. 2 Electromagnetic Force Electromagnetic force is the force between charged particles. In the simpler case when charges are at rest, the force is given by Coulomb’s law : attractive for unlike charges and repulsive for like charges. Charges in motion produce magnetic effects and a magnetic field gives rise to a force on a moving charge. Electric nd magnetic effects are, in general, inseparable – hence the name electromagnetic force. Like the gravitational force, electromagnetic force acts over large distances and does not need any intervening medium. It is enormously strong compared to gravity. The electric force between two protons, for example, 36 is 10 times the gravitational force between them, for any fixed distance. Matter, as we know, consists of elementary charged constituents like electrons and protons. Since the electromagnetic force is so much stronger than the gravitational force, it dominates all phenomena at atomic and molecular scales. (The other two forces, as we hall see, operate only at nuclear scales. ) Thus it is mainly the electromagnetic force that governs the structure of atoms and molecules, the dynamics of chemical reactions and the mechanical, thermal and other properties of materials. It underlies the macroscopic forces like ‘tension’, ‘friction’, ‘normal force’, ‘spring force’, etc. Gravity is always attractive, while electromagnetic force can be attractive or repulsive. Another way of putting it is that mass comes only in one variety (there is no negative mass), but charge comes in two varieties : positive and negative charge. This is what makes all the difference.

Matter is mostly electrically neutral (net charge is zero). Thus, electric force is largely zero and gravitational force dominates terrestrial phenomena. Electric force manifests itself in atmosphere where the atoms are ionised and that leads to lightning. P HYSICAL WORLD 9 Satyendranath Bose (1894-1974) Satyendranath Bose, born in Calcutta in 1894, is among the great Indian physicists who made a fundamental contribution to the advance of science in the twentieth century. An outstanding student throughout, Bose started his career in 1916 as a lecturer in physics in Calcutta University; five years later he joined Dacca University.

Here in 1924, in a brilliant flash of insight, Bose gave a new derivation of Planck’s law, treating radiation as a gas of photons and employing new statistical methods of counting of photon states. He wrote a short paper on the subject and sent it to Einstein who immediately recognised its great significance, translated it in German and forwarded it for publication. Einstein then applied the same method to a gas of molecules. The key new conceptual ingredient in Bose’s work was that the particles were regarded as indistinguishable, a radical departure from the assumption that underlies the classical MaxwellBoltzmann statistics.

It was soon realised that the new Bose-Einstein statistics was applicable to particles with integers spins, and a new quantum statistics (Fermi-Dirac statistics) was needed for particles with half integers spins satisfying Pauli’s exclusion principle. Particles with integers spins are now known as bosons in honour of Bose. An important consequence of Bose-Einstein statistics is that a gas of molecules below a certain temperature will undergo a phase transition to a state where a large fraction of atoms populate the same lowest energy state.

Some seventy years were to pass before the pioneering ideas of Bose, developed further by Einstein, were dramatically confirmed in the observation of a new state of matter in a dilute gas of ultra cold alkali atoms – the Bose-Eintein condensate. If we reflect a little, the enormous strength of the electromagnetic force compared to gravity is evident in our daily life. When we hold a book in our hand, we are balancing the gravitational force on the book due to the huge mass of the earth by the ‘normal force’ provided by our hand. The latter is nothing but the net electromagnetic force between the charged constituents of our hand and he book, at the surface in contact. If electromagnetic force were not intrinsically so much stronger than gravity, the hand of the strongest man would crumble under the weight of a feather ! Indeed, to be consistent, in that circumstance, we ourselves would crumble under our own weight ! 1. 4. 3 Strong Nuclear Force The strong nuclear force binds protons and neutrons in a nucleus. It is evident that without some attractive force, a nucleus will be unstable due to the electric repulsion between its protons. This attractive force cannot be gravitational since force of gravity is negligible compared to the electric force.

A new basic force must, therefore, be invoked. The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength. It is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron. Its range is, however, extremely small, –15 of about nuclear dimensions (10 m). It is responsible for the stability of nuclei. The electron, it must be noted, does not experience this force. Recent developments have, however, indicated that protons and neutrons are built out of still more elementary constituents called quarks. . 4. 4 Weak Nuclear Force The weak nuclear force appears only in certain nuclear processes such as the ? -decay of a nucleus. In ? -decay, the nucleus emits an electron and an uncharged particle called neutrino. The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic forces. The range of weak nuclear force is exceedingly small, of the order of 10-16 m. 1. 4. 5 Towards Unification of Forces We remarked in section 1. 1 that unification is a basic quest in physics. Great advances in physics often amount to unification of different 10 P HYSICS Table 1. Fundamental forces of nature Name Relative strength Range Operates among Gravitational force 10 –39 Infinite All objects in the universe Weak nuclear force 10–13 Very short, Sub-nuclear size ( ? –16 m) 10 Some elementary particles, particularly electron and neutrino Electromagnetic force 10–2 Infinite Charged particles Strong nuclear force 1 Short, nuclear size ( ? –15 m) 10 Nucleons, heavier elementary particles theories and domains. Newton unified terrestrial and celestial domains under a common law of gravitation. The experimental discoveries of Oersted and Faraday showed that electric and magnetic phenomena are in general nseparable. Maxwell unified electromagnetism and optics with the discovery that light is an electromagnetic wave. Einstein attempted to unify gravity and electromagnetism but could not succeed in this venture. But this did not deter physicists from zealously pursuing the goal of unification of forces. Recent decades have seen much progress on this front. The electromagnetic and the weak nuclear force have now been unified and are seen as aspects of a single ‘electro-weak’ force. What this unification actually means cannot be explained here. Attempts have been (and are being) made to unify the electro-weak and the trong force and even to unify the gravitational force with the rest of the fundamental forces. Many of these ideas are still speculative and inconclusive. Table 1. 4 summarises some of the milestones in the progress towards unification of forces in nature. 1. 5 NATURE OF PHYSICAL LAWS Physicists explore the universe. Their investigations, based on scientific processes, range from particles that are smaller than atoms in size to stars that are very far away. In addition to finding the facts by observation and experimentation, physicists attempt to discover the laws that summarise (often as mathematical quations) these facts. In any physical phenomenon governed by different forces, several quantities may change with time. A remarkable fact is that some special physical quantities, however, remain constant in time. They are the conserved quantities of nature. Understanding these conservation principles is very important to describe the observed phenomena quantitatively. For motion under an external conservative force, the total mechanical energy i. e. the sum of kinetic and potential energy of a body is a constant. The familiar example is the free fall of an object under gravity. Both the kinetic energy