1. 1) component of the gravity force parallel to the plane increased 2) coeff. of static friction decreased 3) normal force exerted by the board decreased 4) both #1 and #3 5) all of #1, #2 and #3 A box sits on a flat board. You lift one end of the board, making an angle with the floor. As you increase the angle, the box will eventually begin to slide down. Why? Net Force Normal Weight Sliding Down I

2. m 1) not move at all 2) slide a bit, slow down, then stop 3) accelerate down the incline 4) slide down at constant speed 5) slide up at constant speed A mass m is placed on an inclined plane (  > 0) and slides down the plane with constant speed. If a similar block (same  ) of mass 2m were placed on the same incline, it would: Sliding Down II

3. Tetherball Toward the top of the pole 1) Toward the top of the pole Toward the ground 2) Toward the ground Along the horizontal component of the tension force 3) Along the horizontal component of the tension force Along the vertical component of the tension force 4) Along the vertical component of the tension force Tangential to the circle 5) Tangential to the circle In the game of tetherball, the struck ball whirls around a pole. In what direction does the net force on the ball point? W T

4. You are a passenger in a car, not wearing a seat belt. The car makes a sharp left turn. From your perspective in the car, what do you feel is happening to you? (1) You are thrown to the right (2) You feel no particular change (3) You are thrown to the left (4) You are thrown to the ceiling (5) You are thrown to the floor Around the Curve I

5. (1) centrifugal force is pushing you into the door (2) the door is exerting a leftward force on you (3) both of the above (4) neither of the above During that sharp left turn, you found yourself hitting the passenger door. What is the correct description of what is actually happening? Around the Curve II

6. (1) car’s engine is not strong enough to keep the car from being pushed out (2) friction between tires and road is not strong enough to keep car in a circle (3) car is too heavy to make the turn (4) a deer caused you to skid (5) none of the above You drive your dad’s car too fast around a curve and the car starts to skid. What is the correct description of this situation? Around the Curve III

7. Missing Link A ping-pong ball is shot into a circular tube that is lying flat (horizontal) on a tabletop. When the ping pong ball leaves the track, which path will it follow?

8. Ball and String 1) T 2 = 1/4 T 1 2) T 2 = 1/2 T 1 3) T 2 = T 1 4) T 2 = 2 T 1 5) T 2 = 4 T 1 Two equal-mass rocks tied to strings are whirled in horizontal circles. The radius of circle 2 is twice that of circle 1. If the period of motion is the same for both rocks, what is the tension in cord 2 compared to cord 1?

9. Barrel of Fun A rider in a “barrel of fun” finds herself stuck with her back to the wall. Which diagram correctly shows the forces acting on her? 1 2 3 4 5

10. Going in Circles I 1) N remains equal to mg 2) N is smaller than mg 3) N is larger than mg 4) None of the above You’re on a Ferris wheel moving in a acircle. When the Ferris wheel is at rest, the normal force N exerted by your seat is equal to your weight mg. How does N change at the top of the Ferris wheel when you are in motion?

11. R v 1) F c = N + mg 2) F c = mg – N 3) F c = T + N – mg 4) F c = N 5) F c = mg A skier goes over a small round hill with radius R. Since she is in circular motion, there has to be a centripetal force. At the top of the hill, what is F c of the skier equal to? Going in Circles II

12. R v top 1) F c = T – mg 2) F c = T + N – mg 3) F c = T + mg 4) F c = T 5) F c = mg You swing a ball at the end of string in a vertical circle. Since the ball is in circular motion there has to be a centripetal force. At the top of the ball’s path, what is F c equal to? Going in Circles III

13. You are using a wrench to loosen a rusty nut. Which arrangement will be the most effective in loosening the nut? 1 3 4 2 5) all are equally effective

14. Two forces produce the same torque. Does it follow that they have the same magnitude? 1) yes 2) no 3) depends

15. In which of the cases shown below is the torque provided by the applied force about the rotation axis biggest? For all cases the magnitude of the applied force is the same. 1) F 1 2) F 3 3) F 4 4) all of them 5) none of them

16. When a tape is played on a cassette deck, there is a tension in the tape that applies a torque to the supply reel. Assuming the tension remains constant during playback, how does this applied torque vary as the supply reel becomes empty? 1) torque increases 2) torque decreases 3) torque remains constant

17. 1kg 1m A 1 kg ball is hung at the end of a rod 1 m long. If the system balances at a point on the rod 0.25 m from the end holding the mass, what is the mass of the rod ? 1) 1/4 kg 2) 1/2 kg 3) 1 kg 4) 2 kg 5) 4 kg

18. 1 kg 1 m3 m 1 m2 m ? ? A (static) mobile hangs as shown below. The rods are massless and have lengths as indicated. The mass of the ball at the bottom right is 1 kg. What is the total mass of the mobile ? 1) 5 kg 2) 6 kg 3) 7 kg 4) 8 kg 5) 9 kg