**Problem Set Five**

1. Two 3 kg physical science textbooks on a book shelf are separated by 0.25 m. What is the force of gravitational attraction between the books?

2. What is the force of gravity between two 1000 kg cars separated by a distance of 20 m on a highway?

3. Using the force, calculated in # 2 above, and the weight of the car, calculate:

Force (from #2) divided by the weight of car

4. How would the force of gravity between two masses be affected if the separation distance between them is doubled?

5. How would the force of gravity between two masses be affected if the separation distance between them is decreased by one-half?

6. The separation distance between two 2.0 kg masses is decreased by two-thirds. How is the gravitational force between them affected?

7. A man has a mass of 150 kg. What does he weigh on earth expressed in N?

8. If the gravitation constant on the moon, gm is one-sixth that on the earth, how much does the man in # 7 weigh on the moon?

9. An astronaut on the moon places a package on a scale and finds it weight to be 15 N. What would the package weigh on earth?

10. What is the package’s mass on the moon?