PHYS 1040 (Anger)
Spring 2009
Homework 2
Due Wednesday, January 21
Chapter 4:
1. In what direction does a planet move relative to the stars when it is in
direct motion? When it is in retrograde motion? How do these compare
with the direction in which we see the Sun move relative to the stars?
2. What is the significance of Occam’s razor as a tool for analyzing theories?
3. Is it ever possible to see Mercury at midnight? Explain your answer.
4. List and explain Kepler’s three laws.
5. A line joining the Sun and an asteroid is found to sweep out an area of 6.3
AU2 during 2010. How much area is swept out during 2011? Over a
period of five years?
6. Why does Venus have its largest angular diameter when it is new and its
smallest angular diameter when it is full?
7. What are Newton’s three laws? Give an everyday example of each law.
8. What is the difference between weight and mass?
9. Suppose you traveled to a planet with 4 times the mass and 4 times the
diameter of the Earth. Would you weigh more or less on that planet than
on Earth? By what factor? (
Hint:
Consider the ratio of your weight on
Earth to your weight on the new planet.)
10. The average distance from the Moon to the center of the Earth is 384,400
km, and the diameter of the Earth is 12,756 km. Calculate the
gravitational force that the Moon exerts (a) on a 1-kg rock at the point on
the Earth’s surface closest to the moon and (b) on a 1-kg rock at the point
on the Earth’s surface farthest from the Moon. (c) Find the difference
between the two forces you calculated in parts (a) and (b). This difference
is the tidal force pulling these two rocks away from each other. Explain
why tidal forces cause only a small deformation of the Earth. (
Hint:
This
problem will be much easier if you draw and carefully label a picture of the
Earth/Moon system.)