1. Explain what is *universal* about the law of universal gravitation.

2. As far as Newton was concerned, what did a falling apple have in common with the moon?

3. Gravitational force acts on all bodies in proportion to their masses. Why, then, doesn't a heavy body fall faster than a light body?

4. State and explain the implications of each of Kepler's three laws of planetary motion.

5. Many people mistakenly believe that astronauts that orbit the Earth are "above gravity." Calculate the acceleration due to gravity (*g*) for space shuttle territory, 200 kilometers above the Earth's surface. Earth's mass is 6 x 10^{24} kilograms and its radius is 6.38 x 10^{6} meters (6380 kilometers). Your answer is what percentage of 9.8m/s^{2}?

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6. Why does the force of gravity change the speed of a satellite in an elliptical orbit?

7. What are the restrictions on the orbit of a communications satellite if it is to appear motionless in the sky as viewed from any

location on earth?

8. A projectile is launched upward at an angle. What should this angle be with respect to the horizontal in order for the projectile to travel the farthest distance? Explain why.