Download Quiz 07-2 Rotation

AP Physics
Mrs. Tsarevsky
Name_
Rotational motion
Quiz 7-2
____ 1. What is the angular speed in rad/s of the second hand of a watch?
a) 0.10 rad/s b) 1.7  103 rad/s c) 0.02 rad/s d) 6.28 rad/s
e) 60 rad/s
____ 2. During the spin-dry cycle of a washing machine, the motor slows from 95 rad/s to
30 rad/s while the turning the drum through an angle of 402 radians. What is the
magnitude of the angular acceleration of the motor?
a) 64 rad/s2 b) 32 rad/s2 c) 1.0 rad/s2 d) 20 rad/s2 e) 10 rad/s2
____ 3. The angular measure 1.0 radian is equal to
a) 0.0175° b) 3.14° c) 1.57° d) 57.3° e) 6.28°
____ 4. A grindstone, initially at rest, is given a constant angular acceleration so that it
makes 20.0 rev in the first 8.00 s. What is its angular acceleration?
a) 0.313 rad/s2
d) 3.94 rad/s2
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b) 0.625 rad/s
e) 1.97 rad/s2
c) 2.50 rad/s2
____ 5. A roulette wheel with a 1.0-m radius reaches a maximum angular speed of 18
rad/s before it stops 35 revolutions (220 rad) after attaining the maximum speed.
How long did it take the wheel to stop?
a) 24 s b) 48 s c) 3.7 s d) 8.8 s e) 12 s
____ 6. Complete the following statement: When a net torque is applied to a rigid object,
it always produces a
a) constant acceleration.
d) constant angular momentum.
b) rotational equilibrium.
e) constant angular velocity
c) change in angular velocity..
____ 7. A wrench is used to tighten a nut as shown in the figure. A 12-N force is applied
7.0 cm from the axis of rotation. What is the torque due to the applied force?
a) 0.58 N • m
b) 0.84 N • m
c) 1.71 N • m
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d) 14 N • m
e) 58 N • m
AP Physics
Mrs. Tsarevsky
____ 8. A string is tied to a doorknob 0.79 m from the hinge as shown in the figure. At the
instant shown, the force applied to the string is 5.0 N. What is the torque on the
door?
a) 2.2 N • m
b) 3.3 N • m c) 1.1 N • m
d) 0.84 N • m
e) 0.40 N • m
____ 9. A horizontal, 10-m plank weighs 100 N. It rests on two supports that are placed
1.0 m from each end as shown in the figure. How close to one end can an 800-N
person stand without causing the plank to tip?
a) 0 m
b) 0.2 m
c) 0.6 m
d) 0.5 m
e) 0.8 m
____ 10. One end of a rope is tied to the handle of a horizontally-oriented and uniform
door. A force F is applied to the other end of the rope as shown in the drawing.
The door has a weight of 145 N and is hinged on the right. What is the magnitude
of F at which the door will remain at rest?
a) 145 N b) 265 N c) 381 N d) 424 N e) 530 N
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Name_
AP Physics
Mrs. Tsarevsky
Use the following to answer questions 11-12:
Name_
An 80-kg man balances the boy on a teeter-totter as shown.
Note: Ignore the weight of the board.
____ 11. What is the approximate mass of the boy?
a) 20 k g b) 10 kg c) 40 kg d) 45 kg e) 50 kg
____ 12. What, approximately, is the magnitude of the downward force exerted on the
fulcrum?
a) zero newtons b) 100 N c) 600 N d) 800 N e) 1000 N
____ 13. A string is wrapped around a pulley of radius 0.05 m and moment of inertia
0.2 kg • m2. If the string is pulled with a force F, the resulting angular
acceleration of the pulley is 2 rad/s2. Determine the magnitude of the force F.
a) 0.4 N
b) 2 N c) 40 N d) 16 N e) 8 N
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AP Physics
Mrs. Tsarevsky
____ 14. Three children are pulling on a rotatable platform on a playground. The platform has a
radius of 3.65 m. In the picture, two children are pulling with equal forces of 40.0 N in
an attempt to make the platform rotate clockwise. The third child applies a force of 60
N as shown. What is the net torque on the platform?
Note: "ccw" is counterclockwise and "cw" is clockwise.
a) 73 N • m, cw
b) 73 N • m, ccw
c) 511 N • m, ccw
d) 511 N • m, cw
e) 0 N • m
____ 15. What happens when a spinning ice skater draws in her outstretched arms?
a) Her angular momentum decreases.
b) Her angular momentum increases.
c) Her moment of inertia decreases causing her to slow down.
d) Her moment of inertia decreases causing her to speed up.
e) The torque that she exerts increases her moment of inertia.
____ 16. A spinning star begins to collapse under its own gravitational pull. Which one of
the following occurs as the star becomes smaller?
a) Its angular velocity decreases.
b) Its angular momentum remains constant.
c) Its angular velocity remains constant.
d) Its angular momentum increases
e) Both its angular momentum and its angular velocity remain constant.
____ 17. A 60.0-kg skater begins a spin with an angular speed of 6.0 rad/s. By changing the
position of her arms, the skater decreases her moment of inertia by 50%. What is
the skater's final angular speed?
a) 3.0 rad/s b) 4.5 rad/s c) 9.0 rad/s d) 18 rad/s e) 12 rad/s
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Name_
AP Physics
Mrs. Tsarevsky
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