Physics Principle and Problems

Paul W. Zitzewitz, Todd George Elliott, David G. Haase

Chapter 8

Rotational Motion - all with Video Answers

Educators

Section 1

Describing Rotational Motion

Problem 1

What is the angular displacement of each of the following hands of a clock in 1 h? State your answer in three significant digits.
a. the second hand
b. the minute hand
c. the hour hand

Katie Mcalpine

Katie Mcalpine

Numerade Educator

Problem 2

If a truck has a linear acceleration of $1.85 \mathrm{m} / \mathrm{s}^{2}$ and the wheels have an angular acceleration of $5.23 \mathrm{rad} / \mathrm{s}^{2},$ what is the diameter of the truck's wheels?

Katie Mcalpine

Numerade Educator

Problem 3

The truck in the previous problem is towing a trailer with wheels that have a diameter of $48 \mathrm{cm},$
a. How does the linear acceleration of the trailer compare with that of the truck?
b. How do the angular accelerations of the wheels of the trailer and the wheels of the truck compare?

Katie Mcalpine

Numerade Educator

Problem 4

You want to replace the tires on your car with tires that have a larger diameter. After you change the tires, for trips at the same speed and over the same distance, how will the angular velocity and number of revolutions change?

Katie Mcalpine

Numerade Educator

Problem 5

Angular Displacement A movie lasts 2 h. During that time, what is the angular displacement of each of the following?
a. the hour hand
b. the minute hand

Katie Mcalpine

Numerade Educator

Problem 6

Angular Velocity The Moon rotates once on its axis in 27.3 days. Its radius is $1.74 \times 10^{6} \mathrm{m}.$
a. What is the period of the Moon's rotation in seconds?
b. What is the frequency of the Moon's rotation in $\mathrm{rad} / \mathrm{s} ?$
c. What is the linear speed of a rock on the Moon's equator due only to the Moon's rotation?
d. Compare this speed with the speed of a person on Earth's equator due to Earth's rotation.

Katie Mcalpine

Numerade Educator

Problem 7

Angular Displacement The ball in a computer mouse is $2.0 \mathrm{cm}$ in diameter. If you move the mouse
$12 \mathrm{cm},$ what is the angular displacement of the ball?

Katie Mcalpine

Numerade Educator

Problem 8

Angular Displacement Do all parts of the minute hand on a watch have the same angular displacement? Do they move the same linear distance? Explain.

Katie Mcalpine

Numerade Educator

Problem 9

Angular Acceleration In the spin cycle of a clothes washer, the drum turns at 635 rev/min. If the lid of the washer is opened, the motor is turned off. If the drum requires $8.0 \mathrm{s}$ to slow to a stop, what is the angular acceleration of the drum?

Katie Mcalpine

Numerade Educator

Problem 10

Critical Thinking A CD-ROM has a spiral track that starts $2.7 \mathrm{cm}$ from the center of the disk and ends $5.5 \mathrm{cm}$ from the center. The disk drive must turn the disk so that the linear velocity of the track is a constant $1.4 \mathrm{m} / \mathrm{s}$. Find the following.
a. the angular velocity of the disk (in rad/s and rev/min) for the start of the track
b. the disk's angular velocity at the end of the track
c. the disk's angular acceleration if the disk is played for 76 min

Averell Hause

Carnegie Mellon University