Practice Quiz 7 Angular Speed Centripetal Forces

Practice Quiz 7


1) Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger angular speed?
A) Child A
B) Child B
C) They have the same angular speed.
D) There is not enough information given to answer the question.
Answer: C


2) A compact disk rotates at 210 revolutions per minute. What is its angular speed in rad/s?
A) 11.0 rad/s
B) 22.0 rad/s
C) 69.1 rad/s
D) 660 rad/s
Answer: B


3) A fan is turned off, and its angular speed decreases from 10.0 rad/s to 6.3 rad/s in 5.0 s. What is the magnitude of the angular acceleration of the fan?
A) 0.74 rad/s2
B) 0.37 rad/s2
C) 11.6 rad/s2
D) 1.16 rad/s2
Answer: A


4) A wheel that is rotating at 33.3 rad/s is given an angular acceleration of 2.15 rad/s2. Through what angle has the wheel turned when its angular speed reaches 72.0 rad/s?
A) 83.2 rad
B) 697 rad
C) 66.8 rad
D) 948 rad
Answer: D


5) The escape speed from the surface of the Earth is 11.2 km/s. Estimate the escape speed for a spacecraft from the surface of the Moon. The Moon has a mass 1/81 that of Earth and a radius 0.25 that of Earth.
a. 2.5 km/s
b. 4.0 km/s
c. 5.6 km/s
d. 8.7 km/s
Answer: B


6) Two children ride on a merry-go-round, George is at a greater distance from the axis of rotation than Jacques. It is a true statement that
A) Jacques has a greater speed than George.
B) Jacques and George have the same speed.
C) Jacques has a smaller speed than George.
D) Cannot tell which one has the greater speed without knowing their masses.
Answer: C


7) Because Earth's orbit is slightly elliptical, Earth actually gets closer to the Sun during part of the year. When Earth is closer to the Sun its orbital speed is
A) less than when Earth is farthest away from the Sun.
B) the same as when Earth is farthest away from the Sun.
C) greater than when Earth is farthest away from the Sun.
D) sometimes greater sometimes smaller than when Earth is farthest away from the Sun.
Answer: C

8) How do the escape velocities for two rockets, the first weighing 20 N and the second weighing 20,000 N compare?
A) The escape velocity for the lighter rocket is smaller than that for the heavier rocket.
B) The escape velocity for the lighter rocket is the same as that for the heavier rocket.
C) The escape velocity for the lighter rocket is greater than that for the heavier rocket.
D) It is impossible to compare the two escape velocities.
Answer: B

9) At what location does an artificial Earth satellite in elliptical orbit have its greatest speed?
A) nearest the Earth
B) farthest from the Earth
C) between Earth and Moon
D) between Earth and Sun
Answer: A

10) A child is riding a merry-go-round which completes one revolution every 8.36 s. The child is standing 4.65 m from the center of the merry-go-round. What is the magnitude of the centripetal acceleration of the child?
A) 6.84 m/s2
B) 2.63 m/s2
C) 0.0664 m/s2
D) 0.696 m/s2
Answer: B