Question 1

2 600 rev/min is equivalent to which of the following?

Accepted Answer

A)  2600 rad/s 
B)  43.3 rad/s 
C)  273 rad/s 
D)  60 rad/s

Question 2

Geosynchronous satellites orbit the Earth at a distance of 42 000 km from the Earth's center.Their angular speed at this height is the same as the rotation rate of the Earth,so they appear stationary at certain locations in the sky.What is the force acting on a 1 500-kg satellite at this height?

Accepted Answer

A)  85 N 
B)  333 N 
C)  404 N 
D)  457 N

Question 3

A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s.What is the wheel's average angular acceleration?

Accepted Answer

A)  9.6 rad/s2 
B)  4.8 rad/s2 
C)  1.6 rad/s2 
D)  0.33 rad/s2

Question 4

A point on the rim of a 0.15-m-radius rotating disk has a centripetal acceleration of 5.0 m/s2.What is the angular speed of a point 0.075 m from the center of the disk?

Accepted Answer

A)  0.89 rad/s 
B)  1.6 rad/s 
C)  3.2 rad/s 
D)  5.8 rad/s

Question 5

A Ferris wheel starts at rest and builds up to a final angular speed of 0.70 rad/s while rotating through an angular displacement of 4.9 rad.What is its average angular acceleration?

Accepted Answer

A)  0.10 rad/s2 
B)  0.05 rad/s2 
C)  1.8 rad/s2 
D)  0.60 rad/s2

Question 6

A point on the rim of a 0.25-m-radius fan blade has centripetal acceleration of 0.20 m/s2.Find the centripetal acceleration of a point 0.05 m from the center of the same wheel.

Accepted Answer

A)  0.01 m/s2 
B)  0.02 m/s2 
C)  0.04 m/s2 
D)  0.08 m/s2

Question 7

Starting from rest,a wheel undergoes constant angular acceleration for a period of time T.At what time after the start of rotation does the wheel reach an angular speed equal to its average angular speed for this interval?

Accepted Answer

A)  0.25 T 
B)  0.50 T 
C)  0.67 T 
D)  0.71 T

Question 8

Consider a point on a bicycle tire that is momentarily in contact with the ground as the bicycle rolls across the ground with constant speed.The direction for the acceleration for this point at that moment is:

Accepted Answer

A)  upward. 
B)  down toward the ground. 
C)  forward. 
D)  at that moment the acceleration is zero.

Question 9

What is the angular speed about the rotational axis of the Earth for a person standing on the surface?

Accepted Answer

A)  7.3 × 10−5 rad/s 
B)  3.6 × 10−5 rad/s 
C)  6.28 × 10−5 rad/s 
D)  3.14 × 10−5 rad/s

Question 10

If the mass of Mars is 0.107 times that of Earth,and its radius is 0.530 that of Earth,estimate the gravitational acceleration g at the surface of Mars.(gearth = 9.80 m/s2)

Accepted Answer

A)  2.20 m/s2 
B)  3.73 m/s2 
C)  4.20 m/s2 
D)  5.50 m/s2

Question 11

Consider a point on a bicycle wheel as the wheel makes exactly four complete revolutions about a fixed axis.Compare the linear and angular displacement of the point.

Accepted Answer

A)  Both are zero. 
B)  Only the angular displacement is zero. 
C)  Only the linear displacement is zero. 
D)  Neither is zero.

Question 12

Consider a point on a bicycle wheel as the wheel turns about a fixed axis,neither speeding up nor slowing down.Compare the linear and angular velocities of the point.

Accepted Answer

A)  Both are constant. 
B)  Only the angular velocity is constant. 
C)  Only the linear velocity is constant. 
D)  Neither is constant.

Question 13

Consider a point on a bicycle wheel as the wheel turns about a fixed axis,neither speeding up nor slowing down.Compare the linear and angular accelerations of the point.

Accepted Answer

A)  Both are zero. 
B)  Only the angular acceleration is zero. 
C)  Only the linear acceleration is zero. 
D)  Neither is zero.

Question 14

A 0.30-m-radius automobile tire accelerates from rest at a constant 2.0 rad/s2.What is the centripetal acceleration of a point on the outer edge of the tire after 5.0 s?

Accepted Answer

A)  300 m/s2 
B)  33 m/s2 
C)  30 m/s2 
D)  3.0 m/s2

Question 15

A satellite is in a circular orbit about the Earth at a distance of one Earth radius above the surface.What is the speed of the satellite? (The radius of the Earth is 6.4 × 106 m,and G = 6.67 × 10−11 N⋅m2/kg2. )

Accepted Answer

A)  2 800 m/s 
B)  4 200 m/s 
C)  5 600 m/s 
D)  16 800 m/s

Question 16

If a planet has a radius 20% greater than that of the Earth but has the same mass as the Earth,what is the acceleration due to gravity at its surface?

Accepted Answer

A)  14 m/s2 
B)  12 m/s2 
C)  8.2 m/s2 
D)  6.8 m/s2

Question 17

A fan blade,initially at rest,rotates with a constant acceleration of 0.025 rad/s2.What is its angular speed at the instant it goes through an angular displacement of 4.2 rad?

Accepted Answer

A)  0.025 rad/s 
B)  0.11 rad/s 
C)  0.46 rad/s 
D)  1.2 rad/s

Question 18

Two satellites are monitored as they orbit the Earth;satellite X is eight times as far from the Earth's center as is satellite Y.From Kepler's third law one may conclude that the period or revolution of X is what factor times that of Y?

Accepted Answer

A)  1/2 
B)  2.0 
C)  4.0 
D)  22.6

Question 19

Two objects are in circular orbits of different radii around the Sun.Which object has the highest orbital speed?

Accepted Answer

A)  The one closest to the Sun. 
B)  The one farthest from the Sun. 
C)  Once in orbit around the Sun,all objects have the same orbital speed regardless of distance from the Sun.It is the greater radius and greater resulting circumference that causes the object farther from the Sun to take longer to complete an orbit. 
D)  This cannot be found without knowing the relative masses of the objects.

Question 20

A 0.400-kg object is swung in a circular path and in a vertical plane on a 0.500-m-length string.If the angular speed at the bottom is 8.00 rad/s,what is the tension in the string when the object is at the bottom of the circle?

Accepted Answer

A)  5.60 N 
B)  10.5 N 
C)  16.7 N 
D)  19.6 N

Exam 7: Rotational Motion and the Law of Gravity