lecture1

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Instructor: Dr. Alexey Belyanin Physics 218 Sections 807, 808, 809

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Homepage http://faculty.physics.tamu.edu/belyanin/P218/ Office: Engineering/Physics Office Tower (ENPO), Room 509 Phone 845-7785, email belyanin@tamu.edu Office hours: Tuesday and Thursday 10 am - noon or by appointment

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Textbook: “Don’t Panic: Volume I”, by William H. Bassichis, 5th Edition Crested Butte, 2006

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Grade Policy Exams 45% Lab 5% Quizzes (including homework quizzes) 10% Final 40%

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You must pass both the lecture (3 midterm exams, final exam, homework) and laboratory (>70%) parts of the course separately in order to pass the course Students not taking or failing lab will receive an Incomplete Grade Policy (cont)

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If your grade on the Final Exam is higher than your lowest grade on one of the three exams during the semester, the grade on the Final will replace that one lowest exam grade in computing the course grade (it will only replace one grade in case of two exams having the same lowest grade). The Final Exam grade cannot be used to replace an exam that has been missed without an University excused absence. The missed exam will count as a zero when computing your final grade. Grade Policy (cont)

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All Exams are Closed book No numbers! In general the problems will be formula solutions with variables Problems will be similar to those on homework and recitation

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Similar does not mean identical! Many of you are used to being given formulas and numbers to plug into them… We are not going to do this on the exams! We’ll use variables… If you do the homework the way we ask you to, you’ll be well prepared for the exams!

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Homework You’ll have weekly homework assignments Every Tuesday you’ll have a hw quiz at the beginning of the class with one problem from your assignment. Good news: you are allowed to use YOUR notes (no books or photocopies) No partial credit. You have to show your work, get a correct formula, and, if required, a numerical answer

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Check my webpage for hw assignments Example for Week 1 (Week Aug 27): Week Aug 27 (due Sep 4): All Chapter 1 problems and exercises “Due” means that I’ll give you a hw quiz on that day

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Exam schedule All mid-term exams will be in HELD 105  from 7:00 to 9:30 pm September  25             Exam I October      23             Exam II November  20             Exam III Final             TBA

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Be proactive! Get into it and have fun Be serious about an old rule of thumb: you have to study 2-3 hours a week outside the class per each credit hour Don’t miss classes (lectures, recitations, labs) Solve all problems and exercises after each Chapter in the book Don’t fall into the “I understand the concepts but I can’t do the problems” trap. It means you haven’t done enough of the problems in the chapters. Every year we have students who think they understand but fail during the exams. Don’t let this happen to you!

Why study physics?: 

Why study physics? the most fundamental of the sciences provides the basis of our understanding of the Universe; We do want to find out how things work! scientists of all disciplines make use of the ideas of physics fun to learn and adventure!

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What happens when physics is ignored?

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On January 28, 1986, seven astronauts were killed when the space shuttle they were piloting, the Challenger, exploded just over a minute into the flight. The failure of the solid rocket booster O-rings to seal properly at low temperature allowed hot combustion gases to leak from the side of the booster and burn through the external fuel tank. O-ring

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Douglas Isbell Headquarters, Washington, DC Sept. 30, 1999 (Phone: 202/358-1753) Mary Hardin Jet Propulsion Laboratory, Pasadena, CA (Phone: 818/354-5011) Joan Underwood Lockheed Martin Astronautics, Denver, CO (Phone: 303/971-7398) RELEASE 99-113 MARS CLIMATE ORBITER TEAM FINDS LIKELY CAUSE OF LOSS A failure to recognize and correct an error in a transfer of information between the Mars Climate Orbiter spacecraft team in Colorado and the mission navigation team in California led to the loss of the spacecraft last week, preliminary findings by NASA's Jet Propulsion Laboratory internal peer review indicate. "People sometimes make errors," said Dr. Edward Weiler, NASA's Associate Administrator for Space Science. "The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft." The peer review preliminary findings indicate that one team used English units (e.g., inches, feet and pounds) while the other used metric units for a key spacecraft operation. This information was critical to the maneuvers required to place the spacecraft in the proper Mars orbit. "Our inability to recognize and correct this simple error has had major implications," said Dr. Edward Stone, director of the Jet Propulsion Laboratory. "We have underway a thorough investigation to understand this issue." NASA PRESS RELEASE 09/30/1999

Mechanics: 

Mechanics Various forms of motion: mechanical electromagnetic thermal, etc. Mechanical form of motion: displacements of various bodies relative to each other and changes of the shapes of the bodies Studies mechanical motion of bodies and their interactions Interactions in mechanics are described as forces that change the velocities of the bodies or lead to their deformation For many centuries it was believed that all phenomena in nature are mechanical

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Then physics exploded with discoveries of a vast variety of non-mechanical phenomena: electromagnetic, nuclear, thermal, …

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It turns out that at large scales all these complex interactions cease to be important, and the motion is dominated by the force of gravity and is described by the laws of mechanics.

Historical notes: 

Historical notes

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Ancient times: Greece, China, India, Arab countries Driven by discoveries in astronomy or the need to build machines and weapons Modern period: 15-17 centuries - Galilei, Kepler, Huygens, Hooke, Newton 18th century: driven by tremendous development in mathematics. Euler, D’Alembert, Lagrange, … 20th century: Nonlinear dynamics, chaos, gas dynamics, etc. Poincare, Lyapunov, … Quantum Mechanics; Theory of Relativity

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Archimedes (3rd century B.C.), the law of lever, the law of equilibrium for floating bodies GIVE ME A PLACE TO STAND AND I WILL MOVE THE EARTH

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Antikythera Mechanism decoded?! Found in 1901 near the Antikythera island in a Roman shipwreck dated 80 BC Remained a puzzle for over 100 years Recently deciphered using X-ray tomography, optical imaging, texture mapping

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Nature, 30 November 2006 (page 587)

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A sophisticated mechanical computer

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Predicts: Lunar and solar cycles, taking into account ellipticity of the moon’s orbit Lunar and solar eclipses Accurate positions of the sun, moon, and planets Luni-solar calendar Next time when much simpler mechanisms of this kind appeared was in Islamic countries in 1300 AD (Al Biruni) Later they were imported to Europe and became clock mechanisms It proves technical and scientific sophistication of the Greek civilization that has been lost within Roman Empire

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Aryabhata the Elder Born: 476 in Kusumapura (now Patna), India Died: 550 in India Most accurate value of Pi among ancients! Add four to one hundred, multiply by eight and then add sixty-two thousand. the result is approximately the circumference of a circle of diameter twenty thousand. By this rule the relation of the circumference to diameter is given. This gives π = 62832/20000 = 3.1416 which is a surprisingly accurate value: π = 3.14159265 correct to 8 places! Aryabhata gives a systematic treatment of the position of the planets in space. He gave the circumference of the earth as 24 835 miles, which is an excellent approximation to the currently accepted value of 24 902 miles. He believed that the apparent rotation of the heavens was due to the axial rotation of the Earth. This is a quite remarkable view which later commentators could not bring themselves to follow and most changed the text to save Aryabhata from what they thought were stupid errors! Aryabhata believes that the Moon and planets shine by reflected sunlight, incredibly he believes that the orbits of the planets are ellipses. He correctly explains the causes of eclipses of the Sun and the Moon.

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Aryabhata calculated the Sidereal day (the rotation of the earth against the fixed stars) as 23 hours 56 minutes and 4.1seconds; the modern value is 23:56:4.091. Similarly, his value for the length of the sidereal year at 365 days 6 hours 12 minutes 30 seconds is only 3 minutes 20 seconds longer than the true value (over 365 days). The very notion of sidereal time was very advanced for the time, so this kind of accurate computation speaks of a very sophisticated understanding of the universe. The 8th century Arabic edition of the Āryabhatīya was translated into Latin in the 13th century, well before Copernicus. Through this translation, European mathematicians may have learned methods for calculating sines and cosines (exact to 4 significant digits!), as well as square and cube roots, and it is likely that some of Aryabhata's results also influenced European astronomy.

Arab science: 

Arab science Science in Islamic world was built on the sciences of two great cultures, the Greek and the Indian. Blending and expanding these often different ideas led to a new science which later profoundly influenced Western scientific exploration beginning in the Renaissance. Al-Khwarizmi (9th century), the inventor of algebra. He based the system on the Indian numbers borrowed by the Arabs (what we today call Arabic numerals). Detailed positions of the sun and planets, detailed map of the world. Omar Khayyam was a great Persian scientist, philosopher, and poet who lived from 1048-1131. He made outstanding contributions to mathematics (general theory of cubic equations, conic sections, non-euclidean geometry, Pascal triangle, etc. ) He was ahead of his time by at least 700 years. He compiled many astronomical tables and performed a reformation of the calendar which was more accurate than the Julian and came close to the Gregorian. An amazing feat was his calculation of the year to be 365.24219858156 days long, which is accurate to the 6th decimal place! Actually, 6th decimal place changes over a person’s lifetime. Do you know why?

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Samarkand: Marco Polo’s “most perfectly beautiful city”

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“Five Minute University” All Newtonian mechanics can be formulated on a half of this page: A. Space and time Our space is 3-dimensional and euclidean; our time is 1-dimensional and absolute B. Galilean principle of relativity (Galileo’s ship!) Laws of physics (and everything in the Universe) look the same for all observers who move with a constant velocity with respect to each other. C. Newton’s determinism The motion of a body is uniquely determined by its initial position and velocity. In particular, acceleration is a function of only the position and velocity:

Clockwork universe: 

Clockwork universe

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Language of physics is math First week we will learn some calculus: derivatives and integrals that we’ll need in this course Studies show that you need to be good at math to solve physics problems (This is a skill! Anyone can learn it, you just have to learn to deal with the fear and learn it anyways).