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Unformatted text preview: is a. to the right a. to the right b. to the left b. to the left c. zero c. zero 8. (2 pts) A box that weighs 10 N rests on a table. A 6.0 N force is applied in the horizontal direction, and the box doesn’t move. The coefficient of static friction must be a. equal to 0.60 b. greater than or equal to 0.60 c. less than or equal to 0.60 9. (2 pts) Bob pushes a box at a steady speed along a level floor with a push force that’s 30° below the horizontal. The normal force of the floor on the box is _____ the weight of the box. a. greater than b. less than c. equal to Name__________________________________ 10. At right is graph of the net force vs. time applied to an object. Sketch a qualitatively correct v
t graph on the axes provided. Assume the object begins from rest. (Get the shape right.) (3 pts) 11. A puck moving with a speed of 4.0 m/s slides off the level roof of a building that’s 45 m high. a. How far from the base of the building does it land? (6 pts) 45.0 m
If it slid off going twice as fast, b. (2 pts) the time it takes to land would c. (2 pts) …and the distance it lands from the base i. double of the building would ii. be the same i. double iii.be half ii. be the same iii.be half 12. A block that weighs 100 N rests on an incline. A +y
force diagram for the block is given at right. Find the normal force of the incline on the block. (4 pts) n
+x
fs
€
Fnet = 0
€ 0˚
3
€
w Name__________________________________ 13. You’re standing on a scale in an elevator that’s going up at a constant speed. You observe that the scale reads 500 N. As you approach the top floor, you observe that the scale reading changes to 300 N for 2.0 s until the elevator comes to rest. How fast were you going? (For full credit your solution must include a correct free
body diagram and motion diagram, a solution beginning from fundamental equations, proper units and significant figures.) (12 points)...
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 Fall '07
 Cui
 Physics

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