Tuesday, May 31, 2011

Announcements:

• Note: Based on the vote taken in class this morning, Exam 2 will be held during class on Thursday instead of Wednesday and will still cover chapters 7 through 12. If you want to take this exam on Wednesday, let me know so that I can arrange a time for you to do so.
• Dmitry will hold an extended SI session today from 5:00 – 7:00 pm in Phillips 220.
• I will hold a review Q&A session immediately after class and again at 12:00 today in Phillips 215.

Assignments:

• HW12 is now due tomorrow at midnight.
• RWP for Exam 2 is due tomorrow morning.

Chapter 12 - Gravity

Gravitational force acts between any two objects that have mass:  Fg = G*m1*m2/r^2

Gravitational potential energy:  U = -G*m1*m2/r

Kepler's laws of planetary motion (not emphasized in this course).

Ponderable:  A satellite is in a circular orbit at an altitude above the Earth that is equal to twice the radius of the Earth.  What is the weight of this satellite compared to its weight on Earth, W?

Exercise:  Find the altitude required for a satellite to remain in geosynchronous orbit.

During the 2007 Superbowl, there was a commercial that showed a FedEx office on the moon.  There are at least a dozen examples of "bad" physics in this 30-second advertisement that cost $2.6 million to air.  Here is my summary of the good and bad physics from this ad.