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Physics Lecture Resources

Introduction to Physics and 1-D Motionhappyphysics.comHappy Model Hr. Sec. SchoolUdhampur, IndiaEmail: mineesh.gulati@gmail.comProf. Mineesh Gulati1Text BookPhundamentals of Physics F7th EditionHalliday, Resnick and Walker

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lecturesslidesproblemshappyphysics.com3

Ptolemy

Kepler

Kelper and Tycho-Brahe

Newton

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Marie Curie

Maria Mayer

Yukawa

GalileoIn praise of Physicshappyphysics.com4Mention pictures as they come on.

Of course they realise the following result from clear physics originsSpace explorationModern communications: mobie phone, internet wwwThe World Wide Web began as a networked information project at CERN, where Tim Berners-Lee, now Director of the World Wide Web Consortium [W3C], developed a vision of the project. Tim Berners-Lee 1980

Earth WaterAirFireIn 500 BC Physics was quite simple

KinematicsAstronomyDynamicsObjects stay at rest unless being pushed!happyphysics.com5

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Aristotle384 BC -322 BChappyphysics.com7ristotle, more than any other thinker, determined the orientation and the content of Western intellectual history. He was the author of a philosophical and scientific system that through the centuries became the support and vehicle for both medieval Christian and Islamic scholastic thought: until the end of the 17th century, Western culture was Aristotelian. And, even after the intellectual revolutions of centuries to follow, Aristotelian concepts and ideas remained embedded in Western thinking.

(1971)The retrograde motion in the orbit of mars was a serious challenge to the standard geocentric cosmology which demanded that all the planets orbit the earth. Ptolemy (85-165 AD) came up with an elaborate mechanism to keep the earth at the center of the Universe.September 4July 26June 6October 14

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Ptolemys Epicycles (85-165 AD)

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Crystal sphere with starsParadiseEarthCan you imagine no change to this theory for more than 1000 years!happyphysics.com10

Copernicus ~1540

Earth revolves around the Sun ---365 daysEarth rotates on its axis -- 1 dayhappyphysics.com11Copernicus is said to be the founder of modern astronomy. He was born in Poland,1 and eventually was sent off to Cracow University, there to study mathematics and optics; at Bologna, canon law. Returning from his studies in Italy, Copernicus, through the influence of his uncle, was appointed as a canon in the cathedral of Frauenburg where he spent a sheltered and academic life for the rest of his days. Because of his clerical position, Copernicus moved in the highest circles of power; but a student he remained. For relaxation Copernicus painted and translated Greek poetry into Latin. His interest in astronomy gradually grew to be one in which he had a primary interest. His investigations were carried on quietly and alone, without help or consultation. He made his celestial observations from a turret situated on the protective wall around the cathedral, observations were made "bare eyeball," so to speak, as a hundred more years were to pass before the invention of the telescope. In 1530, Copernicus completed and gave to the world his great work De Revolutionibus, which asserted that the earth rotated on its axis once daily and traveled around the sun once yearly: a fantastic concept for the times. Up to the time of Copernicus the thinkers of the western world believed in the Ptolemiac theory that the universe was a closed space bounded by a spherical envelope beyond which there was nothing. Claudius Ptolemy, an Egyptian living in Alexandria, at about 150 A.D., gathered and organized the thoughts of the earlier thinkers. (It is to be noted that one of the ancient Greek astronomers, Aristarchus, did have ideas similar to those more fully developed by Copernicus but they were rejected in favour of the geocentric or earth-centered scheme as was espoused by Aristotle.) Ptolemy's findings were that the earth was a fixed, inert, immovable mass, located at the center of the universe, and all celestial bodies, including the sun and the fixed stars, revolved around it. It was a theory that appealed to human nature. It fit with the casual observations that a person might want to make in the field; and second, it fed man's ego.Copernicus was in no hurry to publish his theory, though parts of his work were circulated among a few of the astronomers that were giving the matter some thought; indeed, Copernicus' work might not have ever reached the printing press if it had not been for a young man who sought out the master in 1539. George Rheticus was a 25 year old German mathematics professor who was attracted to the 66 year old cleric, having read one of his papers. Intending to spend a few weeks with Copernicus, Rheticus ended up staying as a house guest for two years, so fascinated was he with Copernicus and his theories. Now, up to this time, Copernicus was reluctant to publish, -- not so much that he was concerned with what the church might say about his novel theory (De Revolutionibus was placed on the Index in 1616 and only removed in 1835), but rather because he was a perfectionist and he never thought, even after working on it for thirty years, that his complete work was ready, -- there were, as far as Copernicus was concerned, observations to be checked and rechecked.(Interestingly, Copernicus' original manuscript, lost to the world for 300 years, was located in Prague in the middle of the 19th century; it shows Copernicus' pen was, it would appear, continually in motion with revision after revision; all in Latin as was the vogue for scholarly writings in those days.)Copernicus died in 1543 and was never to know what a stir his work had caused. It went against the philosophical and religious beliefs that had been held during the medieval times. Man, it was believed (and still believed by some) was made by God in His image, man was the next thing to God, and, as such, superior, especially in his best part, his soul, to all creatures, indeed this part was not even part of the natural world (a philosophy which has proved disastrous to the earth's environment as any casual observer of the 20th century might confirm by simply looking about). Copernicus' theories might well lead men to think that they are simply part of nature and not superior to it and that ran counter to the theories of the politically powerful churchmen of the time.

Retrograde motion according to Copernicushappyphysics.com12

happyphysics.com13In 1616 Galileo wrote the Letter to the Grand Duchess which vigorously attacked the followers of Aristotle. In this work, which he addressed to the Grand Duchess Christina of Lorraine, he argued strongly for a non-literal interpretation of Holy Scripture when the literal interpretation would contradict facts about the physical world proved by mathematical science. In this Galileo stated quite clearly that for him the Copernican theory is not just a mathematical calculating tool, but is a physical reality:- I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it. Moreover ... I confirm this view not only by refuting Ptolemy's and Aristotle's arguments, but also by producing many for the other side, especially some pertaining to physical effects whose causes perhaps cannot be determined in any other way, and other astronomical discoveries; these discoveries clearly confute the Ptolemaic system, and they agree admirably with this other position and confirm it. Pope Paul V ordered Bellarmine to have the Sacred Congregation of the Index decide on the Copernican theory. The cardinals of the Inquisition met on 24 February 1616 and took evidence from theological experts. They condemned the teachings of Copernicus, and Bellarmine conveyed their decision to Galileo who had not been personally involved in the trial. Galileo was forbidden to hold Copernican views but later events made him less concerned about this decision of the Inquisition. Most importantly Maffeo Barberini, who was an admirer of Galileo, was elected as Pope Urban VIII. This happened just as Galileo's book Il saggiatore (The Assayer) was about to be published by the Accademia dei Lincei in 1623 and Galileo was quick to dedicate this work to the new Pope. The work described Galileo's new scientific method and contains a famous quote regarding mathematics:- Urban VIII invited Galileo to papal audiences on six occasions and led Galileo to believe that the Catholic Church would not make an issue of the Copernican theory. Galileo, therefore, decided to publish his views believing that he could do so without serious consequences from the Church. However by this stage in his life Galileo's health was poor with frequent bouts of severe illness and so even though he began to write his famous Dialogue in 1624 it took him six years to complete the work. Galileo attempted to obtain permission from Rome to publish the Dialogue in 1630 but this did not prove easy. Eventually he received permission from Florence, and not Rome. In February 1632 Galileo published Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican. It takes the form of a dialogue between Salviati, who argues for the Copernican system, and Simplicio who is an Aristotelian philosopher. The climax of the book is an argument by Salviati that the Earth moves which was based on Galileo's theory of the tides. Galileo's theory of the tides was entirely false despite being postulated after Kepler had already put forward the correct explanation. It was unfortunate, given the remarkable truths the Dialogue supported, that the argument which Galileo thought to give the strongest proof of Copernicus's theory should be incorrect. Shortly after publication of Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican the Inquisition banned its sale and ordered Galileo to appear in Rome before them. Illness prevented him from travelling to Rome until 1633. Galileo's accusation at the trial which followed was that he had breached the conditions laid down by the Inquisition in 1616. However a different version of this decision was produced at the trial rather than the one Galileo had been given at the time. The truth of the Copernican theory was not an issue therefore; it was taken as a fact at the trial that this theory was false. This was logical, of course, since the judgement of 1616 had declared it totally false. Found guilty, Galileo was condemned to lifelong imprisonment, but the sentence was carried out somewhat sympathetically and it amounted to house arrest rather than a prison sentence. He was able to live first with the Archbishop of Siena, then later to return to his home in Arcetri, near Florence, but had to spend the rest of his life watched over by officers from the Inquisition. In 1634 he suffered a severe blow when his daughter Virginia, Sister Maria Celeste, died. She had been a great support to her father through his illnesses and Galileo was shattered and could not work for many months. When he did manage to restart work, he began to write Discourses and mathematical demonstrations concerning the two new sciences.

On 31 October 1992, 350 years after Galileo's death, Pope John Paul II gave an address on behalf of the Catholic Church in which he admitted that errors had been made by the theological advisors in the case of Galileo. He declared the Galileo case closed, but he did not admit that the Church was wrong to convict Galileo on a charge of heresy because of his belief that the Earth rotates round the sun.

Galilei Galileo 1564 - 1642

happyphysics.com14Galileo has graciously decided to answer some of our questions about his inventions and discoveries throughout his lifetime. Some of these include the improvement of the telescope, the invention of the pendulum and the theory of falling bodies. Q. When and where were you born? A. I was born in Pisa, Italy on February 15, 1564. Q. Do you have a father and a mother? A. My father is Vincenzo Galilei, who was a musician, and my mother is Giulia delgi Ammannati. Q. Where did you first start your education? A. In 1581, I started studying at the University of Pisa. My father wanted me to study medicine at this University. At the University, though, I studied the physics of Aristotle. Q. Some have known you as a discoverer. What do you think is your most memorable discovery, and why? A. I would have to think the pendulum because it was mere luck that I discovered it. This happened when I was sitting in Church listening to an extremely boring sermon when I happened to look up and see a lamp swinging. I noticed that each time the wind blew it; the lamp took the same time to complete a swing. Q. Did you continue any more observations with the pendulum, and if you did what are they? A. Yes I did. Around 1602, I came up with a law that applies to the pendulum. The law is that the period isn't affected by the arc of the isochronisms. I then tried to make a tool which measures time, but could not because of the inaccurate machines at this time. Q. Some people say that you put holes at the base of the Leaning Tower of Pisa. Why? A. I guess you could state it that way, but in other words I was performing an experiment. Aristotle once stated that heavier objects fell faster than lighter ones. I questioned his theory after my studying of physics at the University of Pisa. The conclusion of my theory was that all objects fall at the same time regardless of the density. I tested my theory by dropping objects from various heights. One of them was performed at the Leaning Tower. I dropped two cannon balls of different weight at the same time. They seemed to land at same time. Q. Did you invent the telescope? And if you didn't, what did you do with it? A. I did not invent it, but made a similar model to the other telescopes of that time. The telescopes of that time had a weak magnification power and didn't apply to my needs. I created another telescope that had a far greater magnification. I discovered great things about our universe with this telescope. Q. What are some of these discoveries that you found with your telescope? A. I found that the moon was not a perfect sphere as Aristotle proposed, but had many mountains and craters. I also observed a supernova, discovered the four planets of Jupiter, and verified the phases of Venus. All of these supported the Copernican theory, which I agree with. Q. Why do you think the Catholic Church has not done much about your agreement with the Copernican theory and what do you think they might do? A. Right now I am finishing up a book, Dialogue Concerning the Two Chief World Systems, which presents these two theories about the universe. Pope Urban VIII wanted me to side with Aristotle, but I will choose not to. I do not care of my fate because the world should learn the truth of our universe, and not some false testimony. The Copernican theory is correct because Aristotle stated that the universe is never changing, but a supernova has appeared in the sky over the years.Keplers Laws of Planetary MotionJohannes Kepler 1571-1630

Law 1The planets circulate in eliptical orbits with the sun at one focusLaw 2A line joining the planet to the Sun sweeps out equal areas per unit time.happyphysics.com15

The law of areasWhen closer to the sun, the planet moves fasterhappyphysics.com16

A CHRONOLOGY OF THE SCIENTIFIC REVOLUTION

1440 Gutenberg completed his wooden press which used metal moving type.

1543 Nicolas Copernicus publishes On The Revolutions of the Heavenly Spheres

1571 Tycho Brahe develops instruments for precise astronomical observation and records positions of stars and planets. He creates a Tychonic System of the cosmos called geoheliocentric. Planets revolve around the sun, while the sun and planets still revolve around the central earth

1609 Johannes Kepler publishes his first and second Laws of Planetary motion. (l) Planetary orbits are elliptical. (2) Planets sweep out equal areas in equal times

1609 Galileo Galilei develops a telescope of 30X magnification and begins observations

1619 Kepler announces his Third Law of Planetary Motion which stated that a planet's distance from the sun is related to the time it takes a planet to revolve around the sun

1632 Galileo publishes his Dialogues on the Two Chief Systems of the World which popularized the Copernican system and articulated the concept of a world subject to mathematical laws

1633 Galileo is denounced by the Inquisition and forced to recant his belief in Copernican theory

1667 Sir Isaac Newton constructs the first reflecting telescope

1687 Newton publishes his Principia Mathematica which explained gravitation, contained the components of Newtonian Physics (matter, motion, space, attraction), and challenged the Aristotelian/Ptolemaic cosmos.

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JOHANNES VERMEER~1660 The year Newton postulated gravity!

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The Astronomer Vermeer 1668

The Geographer Vermeer 1668/9These paintings reflect the blossoming of scientific enquiry in seventeenth century Europe.

At this time, Newton is making the first reflecting telescopes,

Louis XIV is building an observatory in Paris,

the satellites of Jupiter are being used for navigation at sea, and

Huygens has discovered the sixth satellite of Saturn.

The old views, that it would be presumptive for man to probe too closely the sky or the Earth, are being replaced by modern principles of science. happyphysics.com19

Woman peeling potatoes Gabriel Metsu (~1660)

Courtyard (1658)Pieter de Hooch

Milkmaid Vermeer (~1660)Sick Child

Sick Child Gabriel Metsu (1660)At this time artists began to paint pictures of everyday people and events.

Women and their children

The everyday tasks of caring for a family

The caring love for a sick childhappyphysics.com20

Monteverdi

Bach

Vivaldi

ScarlattiPurcell

MozartHandel

And over this same period, as Physics became liberated and questioning, as architecture flourished, and art became less constrained and reflected the real world, there developed a blossoming of music.

The baroque period: new enlightened and liberated forms of music, and newly developed instruments.

The chamber works of Vivaldi

The splendor of Bachs organ works

The choral works of Monteverdi and Handel

The new opera works of Purcell

The genius of Mozart

So we see that in this revolutionary time, Physics was ready for Newton (born in1643), to revolutionize our understanding of mechanics..

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Isaac Newton1642-1727

Gravity

happyphysics.com22Why is it so!!!Riding a bikeThe unstable topRacing down hillhappyphysics.com23For you to read by next lectureReview of Year 12 Physics2.3 Defining position in 1D2.4-2.6 Definitions of average and instantaneous speed and acceleration in 1D. The relationships between these2.7 The case of constant acceleration (VCE Physics)

Read this for next lecture3.2- 3.6 Specifying vectorsSections from the Text book:happyphysics.com24

For Next Lecture:What is her average speed?What is her average velocity?What do you mean by velocity?

To think about:1 km2 kmIf she rode directly to school, what would be her speed? Velocity?I will quiz you on this next lecture.happyphysics.com25

Here endeth the lessonlectureNo. 1

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m

K

M

rJohannes KeplerIsaac Newton

Consider leaving this to laterhappyphysics.com27

If it is moving with a constant velocity, IT WILL CONTINUE TO DO SOIn the absence of a FORCE

a body is at rest 1760 BCA body only moves if it is driven.

In the absence of a FORCE

A body at rest WILL REMAIN AT REST350 BC

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40%QP. R

29Rectilinear MotionStraightlineMotionKinematicsHOW things moveDynamicsErect = straightWHY things move

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happyphysics.com31xDistance travelled in equal time intervalshappyphysics.com32xTime (t)Dist (x)xxxxhappyphysics.com33Time (t)Dist (x)xx1t1x2x3x4x5t2t3t4t5

DxDtAverage speedspeed = distance . time takenhappyphysics.com34If we want to find the AVERAGE speed of the particle, we know it takes a time t to move a distance x).

So

Gradient of the x-t curveTime (t)Dist (x)xx1x2x3x5x6t3x4t4DxDtx4t4DxDt

Instantaneous speed

happyphysics.com35To find the INSTANTANEOUS SPEED we make the time interval smaller and smaller until as it approaches zero we have

If we know x(t), we can find v(t)

Position (x)Position as a function of timehappyphysics.com36

If we know x (t), we can find v(t)

timetimetimeSpeed as a function of timehappyphysics.com37

If we know x (t), we can find v(t)

Similarly if we know v(t), we can find a(t) since

timetimetimeAcceleration as a function of timehappyphysics.com38If we know a(t), we can find v(t), since:

And from v(t) we can find x(t), since

From acceleration speed distancehappyphysics.com39If acceleration is constant, life is easy! VCE easyt0 t (t)(accel) (t)speed v0

Similarly x-x0= v0t + at2v2 = v02 + 2as etc.

if t0 = 0, See slide lect 2happyphysics.com401-D (linear kinematics)with constant acceleration

VCE PhysicsSee modified slide lecture 2happyphysics.com2-D KinematicsVectorshave magnitude and directiondistance displacementspeed velocityhappyphysics.com42

Distance from Melbourne to Bendigo = 1600 km Displacement of Bendigo rel. to Melbourne = 200 km (NW)Average velocity = displacement/time = 200/2 = 100 km/hN.W.Average speed= distance/time = 1600/20 = 80 km/hhappyphysics.com43YXP1 (x1, y1)P2 (x2, y2)y1y2x1x2r1r212r1 = ix1 + jy1 +( kz1)r2 = ix2 + jy2 +( kz1)rr = i(x2- x1) + j(y2-y1) +r = i x + j y +yxr = r2 - r1r = (ix2 + jy2) -(ix1 + jy1) r1 is the vector displacement of P1rel to originr2 is the displacement vector of P2 rel to origin r is the displacement vector of P2 rel to P1The length of r1=

Unit vectors happyphysics.com44Motion in 2 and 3 dimensions4.2Specifying position

P1 (x1, y1)P2 (x2, y2)12rYXy1y2x1x2r1r2yx

Average velocityVav is in direction of Dr Instantaneoushappyphysics.com45Motion in 2 and 3 dimensions4.3Specifying velocity