Class 19, 3/10/05
* We did the last "Thursday bonus-pt exercise:" explain the two important
applications of Kepler's 3rd law via Newton.
* Thanked Ms. Ryan and her assistant Aaron for the good work of supplying
and maintaining the multimedia facility at Roessler.
* Thanked Mr. Greer, the TA, for his excellent work for the course. His prompt
grading of the HWs sets a record, giving back graded HW & solution
every Thursday while receiving the HW on the prior Tuesday. I am most appreciate
his agreement with me that we should provide solutions to the students in
the clearest, yet the simplest presentation. By the solutions reached students,
they usually went through a third revision. Not only didn't he mind, he enjoyed
** the simple math of the two important applications
of Kepler's 3rd law via Newton;
** the v - r plots of a merry-go-around,
of the planets orbiting around the Sun, and of the stars in Milky Way;
** the v -r plots give evidence of
dark matter in Milky Way;
* Showed the animation of shooting an cannon ball. The fate of a cannon ball
depends upon the initial condition of how fast it is fired: recollapsing,
critical, and coasting.
* Made the analogy with the possible fates of the universe: ecollapsing,
critical, coasting, and accelerating.
* Orbiting objects around the Earth or around the Sun does not have the accelerating
fate. (It would be most striking, if they had. It would be like the possibility
of an object would fly off when you through it upwards.
* Discussed the timeline of the universe, and emphasized the experimentally
established parts: recombination, reionization, birth of stars, including
the Sun, and now. They are also documented in HW10 MC part.
* Handed out teaching evaluation and asked Ms. Hirayama and Mr. Hill to collect
and deliver them to the Physics Department.
* Handed out in the back, graded HW9 and solution, and HW10, the MC part
* Wrapping up the course
** Review our discuss in the previous Class about the
fate of planets
** Discuss the fate of our universe.