A circular disk is rotating about a central axis with an angular velocity which is increasing at a constant rate. Point 1 on the disk is located at a distance r1 from the center of the disk and point 2 on the disk is located at a distance r2 from the center of the disk. If r2 = 2r1, which of the following ratios is the largest? 1 and 2 refer to being at points 1 and 2 in the subscripts below, all values occurring at the same time.
a. 2/1 b. 2/1
c. ac2/ac1 d. All the ratios are 1 so none is larger.
[Ques. 2] A ceiling fan is turned on and reaches an angular speed of 132 rev/min in 20 s. It is then turned off and coasts to a stop in an additional 40 s. The ratio of the average angular acceleration for the first 20 s to that for the last 40 s is which of the following?
a. 6.6
b. 6.4
c. 0.15
d. 2.0
[Ques. 3] A spool of thread has an average radius of 1.00 cm. If the spool contains 47.5 m of thread, how many turns of thread are on the spool? Average radius allows us to not need to treat the layering of threads on lower layers.
a. 15.1
b. 756
c. 149
d. 7.56
[Ques. 4] What is the angular speed about the rotational axis of the Earth for a person standing on the surface?
a. 7.3 105 rad/s
b. 3.6 105 rad/s
c. 6.3 105 rad/s
d. 3.1 105 rad/s
[Ques. 5] An object of mass m and moment of inertia I has rotational kinetic energy KER. Its angular momentum is:
a. 0.5 I/m. b. (2 IKER)1/2.
c. (2 mKER)1/2 d. not given.
[Ques. 6] An object with mass m and moment of inertia I is spinning with an angular momentum L. Its kinetic energy is:
a. 0.5I2/L. b. 0.5L2/I.
c. 0.5L2/m. d. 0.5I2/m.
[Ques. 7] An astronaut is on a 100-m lifeline outside a spaceship, circling the ship with an angular speed of 0.100 rad/s. How far inward can she be pulled before the centripetal acceleration reaches 4g = 39.2 m/s2?
a. 50.0 m b. 70.6 m
c. 72.7 m d. 89.9 m
[Ques. 8] A tetherball is attached to a pole with a 2.0-m rope. It is circling at 0.20 rev/s. As the rope wraps around the pole, it shortens. How long is the rope when the ball is moving at 6.0 m/s?
a. 1.8 m b. 0.83 m
c. 1.2 m d. 1.0 m
[Ques. 9] A turntable has a moment of inertia of 3.0 102 kgm2 and spins freely on a frictionless bearing at 25 rev/min. A 0.60-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.10 m from the center. By what factor does the kinetic energy of the system change after the putty is dropped onto the turntable?
a. 0.91 b. 1.0
c. 0.83 d. 1.5
[Ques. 10] A turntable has a moment of inertia of 3.00 102 kgm2 and spins freely on a frictionless bearing at 25.0 rev/min. A 0.600-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.100 m from the center. By what factor does the angular momentum of the system change after the putty is dropped onto the turntable?
a. 1.22 b. 1.00 (no change)
c. 0.820 d. 1.20
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