Physics 201

Why the Sky is Blue

Welcome to Cornell's Physics 201, Why the Sky is Blue. Lectures are on Tuesday and Thursday at 2:55 pm in Rockefeller Hall, Schwartz Auditorium. Recitation sections are all on Wednesday at 9:00 (#5), 2:30 (#'s 1 & 2) and 3:35 (#'s 3 & 4).

We will be using an instant response system during lecture. Make sure you have your I-clicker which you can purchase in the bookstore. You will be expected to have it with you at all lectures.

To register your I-clicker, go to : I-clicker registration

Course instructor is Prof. Ahren Sadoff (ajs50@cornell.edu). Phone: 255-4882 (Wilson Lab), 255-7162 (Clark Hall office)

Office hours: Room 111, Clark Hall, 1:30--2:30 Tuesday and Thursday (or by appointment)

Teaching Assistants are:

(sections #1, #3,) Greg Hallenbeck glh59@cornell.edu
(sections #4, #5) David Curtin drc39@cornell.edu
( #2) Vasso Kanellopoulos vk83@cornell.edu

Note: Calculators will be needed for the final exam

Final exam Review session schedule:

Preliminary Exams and Final Exam schedule

All examinations will be in Schwartz Auditorium during class time unless otherwise noted

Prelim I : Thursday, October 9, 2008 ----- Tentative
Prleim II: Thursday, November 13, 2008 ----- Tentative
Final Exam: Tuesday, December 11, 7:00 --9:30 pm

Web site for

Homework Assignments and Review of Key Ideas

Homework is due at the beginning of next weeks Wednesday's recitation section after assigned.
Readings are from Prof Sadoff's book notes which will be handed out in class

Week 1, Aug. 28 -- Sept. 2

Written assignment #1 handed out in lecture
Key Ideas: Definition of physics and assumptions, Methodology of Science: experimentation (control of variables), need a quantatative description of Nature

Week 2, Aug. 30 -- Sept.5

No written assignment
Key Ideas:Theories: what are they, can they be proven? Aesthetic judgements. Motion-- why begin with this ?, variables to describe motion, defintion of v and a, scalars and vectors, graphs of 1-dimensional motion for constant v and constant a;

Week 3, Sept. 6 -- Sept.12

Written Assignment #2 (due 9/12)
Key Ideas: 2-dimensional motion -- in circular motion the acceleration vector points radially inward.Forces: The Four Fundamental forces; specific force law---Gravity; What does the equation tell us ? Newton's 2-nd law; What is the meaning of F ? Combining Newton's 2-nd law and the law of Gravity; What is the result ? The mass of the Earth; how do we find it ? The Cavendish experiment.Newtomian mechanics; Newton's 1-st, 2-nd and 3-rd Laws of motion.

Week 4, Sept. 13 -- Sept. 19

Written Assignment: NONE
Key Ideas: Effect of Newtonian ideas on society. Electricity and Magnetism:Electric force law, Ampere's law,Faraday's law.Where are the moving charges in a bar magnet? Non-contact forces. How do we understand them ?--- The Field concept vs Action-at-a-distance.

Week 5, Sept. 20 -- Sept. 26

Written Assignment: Pendulum Experiment (due 9/26)
Key Ideas: Evidence for the Field concept ? Are there really contact forces after all? The Character of Physical Laws: Causality, The Prime Directive, Symmetry --

Week 6, Sept. 27 -- Oct.3

Written Assignment: Assignment #4, Momentum and Energy Conservation (due 10/3)
Key Ideas: "Tranlslation" and "reflection" symmetries. Some are "broken"-- that's good for us !! Conservation Laws --- due to some symmetries. Momentum and the Law of Conservation of momentum.More on conservation of momentum, Conservation of Energy-- different forms.

Prelim I on Oct. 4, Fall Break Oct.6 -- 9

Week 7, Oct. 11 -- Oct.17

Key Ideas: The Atom; the history of different atomic models,atomic spectra-- the atom's "fingerprints"Details of the Atom, Atomic Spectra, Definition of the Electron Volt(eV and MeV) and different energies in eV(and MeV) units. The Nucleus: constituents, what holds it together, decays-- Alpha, Beta and Gamma,

Week 9, Oct. 18 -- Oct. 24

Written Assignment #5: The nucleus and nuclear decays (due. 10/24),optional make-up Pendulum experiment (also due 10/24)
Key Ideas: Half life, Carbon dating:how it works, assumptions and verification.The Beta Decay story.

Week 10, Oct. 25 -- Oct. 31

Written Assignment #6: Carbon Dating (due 10/31)
Key Ideas: Introduction to Relativity: Galilean Relatvity, v = v' + u (addition of speeds). The Principle of Galilean Relativity, Inertial reference frames, Maxwell and light is a wave, the difference in measuring the speeds of particles and waves, measuring the speed of an airplane through the air. The Ether--- a universal medium. What is the speed of the earth through the Ether ? Can we measure it in a similar manner to the pilot in the airplane ? Why not ?, the Michelson-Morley experiment--- what did it try to measure ? How did it try to do it ? What was observed ?

Week 11, Nov.1 -- Nov. 7

Written Assignment #7: Relativity I (due 11/7)
Key Ideas: What are the explainations for the observation in the MM experiment ? Which one do we believe to be correct ? A consequence of the speed of light being the same for all observers; can 2 = 1 ?? A simple experiment for two observers moving wrt each other to measure the speed of light --- what was the matter with the analysis ? The three assumptions -- what are they ? The Postulates of Special Relativity, The Relativity of Simultaneity

Prelim II on Nov. 15

Week 12, Nov. 8 -- Nov. 14

Written Assignment: Assignment #8, Relativity #2 ,(Due Nov. 20 in lecture)
Key Ideas: Time Dilation, proper time vs. "Dilated time", the varaiables beta and gamma, Length Contraction, proper length vs. "Contracted length", More on Length Contraction, The Relativity of Simultaneity is crucial in understanding this, was Lorentz right after all ? Other relations involving gamma; Energy and mass. E=mc2 .

Week 13, Nov. 20 ( Happy Thanksgiving )

Written Assignment: Assignment #9, Relativity #3 ,(Due Nov. 28)
Key Ideas:, Back to addition of speeds equation-- Einstein gets it right. Doppler Effect, expansion of the Universe, Twin Paradox. The car in the garage paradox.

Week 14, Nov. 27 -- Nov. 29 ( last week )

Written Assignment: Term Essay (Due Wed. Dec. 5 to your TA by noon)
Key Ideas: The nature of light; properties of waves and particles. Interference and diffraction. Is light a wave or a particle ?--- demonstrations. Why the Sky is Blue. The Electromagnetic spectrum and what is "waving".

Ahren Sadoff <ajs@lns.cornell.edu >

Last modified: Tue Sep 2 12:02:37 EDT 2008

General Relativity---- Principle of Equivalence, the bending of light by gravity, Gravitational red shift, Black Holes, clocks run slower the stronger the gravitational field. +