1. The S.I. units of force are
a) kg b) kg m2/s2 c) kg s/m d) kg m/s e) kg m/s2
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2-7. Consider a 22 kg block of ice in an ice-house.
2-4. The 22 kg block of ice slides across a horizontal floor.
2. If a worker applies a constant horizontal force of 7 N to the block as the block slides frictionlessly, the block must have a constant
a) acceleration of 3.14 m/s2. b) acceleration of 0 m/s2. c) velocity of 3.14 m/s.
d) velocity of 0.318 m/s. e) acceleration of 0.318 m/s2.
3. If the worker suddenly stops applying the 7 N force as the block slides frictionlessly, the block of ice will
a) move with a constant acceleration. b) move with a constant velocity
c) suddenly stop. d) gradually slow to zero velocity.
4. If the acceleration of the block was 0.100 m/s2 when the horizontal force of 7 N was being applied, you might conclude that a frictional force of __________ N was also acting on the block.
a) 6.3 b) zero c) 9.2 d) 4.8 e) 2.2
5-7. The 22 kg block of ice then slides frictionlessly up a ramp tilted at 30 degrees above the horizontal and the worker stops pushing.
5. As the block slides up the ramp, the normal force equals __________ N.
a) 19.1 b) 186.7 c) 215.6 d) 22 e) 107.8
6. The decelleration of the block as it slides up the ramp is __________ m/s2.
a) 9.8 b) 8.48 c) 4.9 d) 0.500 e) 0.866
7. Which of the following forces is present in a free body diagram of the block sliding up the ramp?
a) A frictional force pointing up the ramp. b) A weight force pointing vertically down.
c) A horizontal force of 7 N. d) A normal force pointing vertically up.
e) All of the previous.
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8. The weight of a vehicle on the moon is about 1/6 its weight on earth. The net force needed on the moon to give it the same horizontal acceleration as on earth is __________ .
a) smaller since weight is less b) larger c) smaller since mass is less
d) the same since weight and mass changes cancel. e) the same since mass is same
9. A 10 kg mass hangs by a rope from the ceiling of an elevator as the elevator accelerates upward at 3 m/s2. The tension in the rope is
a) < 98 N b) 98 N c) 30 N d) 0 N e) > 98 N
10. I'm a little tired. While I take a rest
a) don't wake me up. b) subtract 5 points from my score.
c) mark this question wrong. d) MARK THIS QUESTION CORRECT.
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11-13. A bright red pickup truck traveling on level ground rounds a 15 m radius curve at a constant speed of 11 m/s without sliding.
11. As the truck is rounding the curve, its acceleration is
a) directed radially outward. b) increasing. c) directed tangent to the path.
d) directed radially inward. e) zero.
12. The magnitude of the truck's acceleration is __________ m/s2.
a) 0.733 b) 0 c) 8.07 d) 20.5 e) 9.8
13. Since the truck didn't slide, the coefficient of static friction between the truck's tires and the road must be at least as large as
a) 0.52 b) 1.00 c) 0.823 d) 0.15 e) 0.075
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14. The home planet of E.T. has a mass of 3 x 1024 kg (less than that of earth) and on its surface g = 9.8 m/s2 (the same as on earth). The radius of the planet must be _____ m.
a) 6.38 x 106 b) 2.04 x 1013 c) 2.13 x 103 d) 4.52 x 106
15. A satellite orbits Mars at a distance above the Martian surface equal to 3 times the radius of Mars. The acceleration of the satellite is _____ times the acceleration due to gravity on the surface of Mars.
a) 1/3 b) 1 c) 1/16 d) 1/9 e) zero
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16-19. Matthew does 575 J of work as he exerts a force of 60 N on a rope tied to his sister Sarah's sled. Sarah and her sled have a mass of 35 kg and move 12 m across a horizontal icy surface.
16. The rope makes an angle of _____ degrees with the horizontal.
a) 38.6 b) 0 c) 53 d) 37 e) 51.4
17. If Sarah and her sled start out at rest and slide frictionlessly across the ice, her speed after traveling 12 m will be _____ m/s.
a) 5.7 b) 16.4 c) 4.1 d) 3.4 e) 32.9
18. If a frictional force of 15 N also acts on the sled as it slides 12 m across the ice, the change in the kinetic energy of Sarah and her sled will be _____ J.
a) 180 b) 560 c) 575 d) 755 e) 395
Depending on how you interpret what the kinetic energy has changed from, (a) is also a possible correct answer and the posted results include this correction.
19. If in the previous question the mass of Sarah and her sled was doubled, the change in the kinetic energy would be ____ times the answer to the previous question. (The frictional force of 15 N is still acting.)
a) 1 b) 1/2 c) 2 d) 1/4 e) 4
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20. A force of 7 N acts on an object that moves a distance of 10 m. The work done by the force on the object must
a) equal -70 J. b) equal 0 J. c) be positive. d) equal +70 J.
e) lie between -70 J and +70 J.
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Last updated on 11/11/99