1. The motion of a particle connected to spring is described by x = 10 cos (2pt). At what time (in s) is the potential energy equal to the kinetic energy?


a. 0
b. 0.125 c. 0.25 d. 0.50 e. 1.0

2. A truck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. If the frequency of the siren relative to the police car is 500 Hz, what is the frequency heard by an observer in the truck as the police car approaches the truck? (The speed of sound in air is 343 m/s.)


a. 361 b. 668 c. 396 d. 636 e. 393

3. A rock is projected from the edge of the top of a building with an initial velocity of 12.2 m/s at an angle of 30° above the horizontal. The rock strikes the ground at a horizontal distance of 25 m from the base of the building. Assume that the ground is level and that the side of the building is vertical. How tall is the building?

13.0 m 
b) 29.6 m 
c)23.6 d)18.9

4. The position of a particle moving along the x axis is given by x = 5 + 6.0t2 -1.0t3, where x is in meters and t in seconds. What is the position of the particle when it achieves its maximum speed in the positive x direction?


a. 24m b. 21m c. 32m d. 16m e. 2.0m

5. Determine the minimum area of a flat ice floe 1.0 meter thick if it is to support a 4 000-kg truck above seawater. (rice = 920 kg/m3, rsea = 1020 kg/m3.)


a. 20m2
 b. 40m2 c. 60m2 d. 80m2 e. 100 m2

6. A uniform ladder 15 ft long is leaning against a frictionless wall at an angle of 53° above the horizontal. The weight of the ladder is 30 pounds. A 75-lb boy climbs 4.0-ft up the ladder. What is the magnitude of the friction force exerted on the ladder by the floor?


a. 43lb b. 26lb c. 34lb d. 47lb e. 24lb