1. Lots of fun! Win valuable prizes!

2. 1. Two people sit on a balanced seesaw. When one person leans toward the center of the seesaw, that person's end of the seesaw will A. stay at the same level B. rise C. fall

3. 2. You tie a can to a string and whirl it above your head. If you keep the length of the string the same and whirl the can faster and faster, the force you exert on the string A. stays the same. B. increases. C. decreases.

4. 3. If an object is in stable equilibrium, any displacement will A. decrease its mass. B. increase its mass. C. neither raise nor lower its center of gravity. D. lower its center of gravity. E. raise its center of gravity.

5. 4. Which of the following is NOT a unit of rotational speed? A. Rotations per second B. Revolutions per second C. Rotations per minute D. Meters per second E. Revolutions per minute

6. 5. Torque is defined as _____. A. force times time B. mass times acceleration C. mass times velocity D. force times lever arm E. momentum times radius

7. 6. Which has greater linear speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail? A. The outside horse B. The inside horse C. Neither—they both have the same linear speed.

8. 7. A meter stick is balanced at the 50-cm mark. You tie a 20-N weight at the 60-cm mark. Where should a 10-N weight be placed so the meter stick will again be balanced? A. 20 cm mark B. 30-cm mark C. 60-cm mark D. 70-cm mark E. 90-cm mark

9. 8. An object thrown into the air with a spin rotates about its A. midpoint. B. geometric center. C. center of gravity. D. edge. E. none of the above

10. 9. If an object is in unstable equilibrium, any displacement will A. lower its center of gravity. B. decrease its mass. C. raise its center of gravity. D. neither raise nor lower its center of gravity. E. increase its mass.

11. 10. If an object is in neutral equilibrium, any displacement will A. increase its mass. B. raise its center of gravity. C. neither raise nor lower its center of gravity. D. lower its center of gravity. E. decrease its mass.

12. 11. A car travels in a circle with constant speed. The net force on the car A. is directed toward the center of the curve. B. is zero because the car is not accelerating. C. is directed forward, in the direction of travel. D. none of the above

13. 12. Suppose you try loosening a nut with a wrench, and the nut doesn't give at all. You increase your chance of success if you _____. A. extend the lever arm B. have a friend help you pull on the wrench C. exert a larger force D. be sure to exert force perpendicular to the lever arm E. all of the above

14. 13. Which has greater rotational speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail? A. The outside horse B. The inside horse C. Neither—they both have the same rotational speed.