Conceptual Physics

Chapter 8 Problems

Conceptual Problems

C.1 A string's tension force supplies the centripetal force needed to keep a yo-yo whirling in a circle. (a) What force supplies the
centripetal force keeping a satellite in uniform circular motion around the Earth? (b) What kinds of forces keep a roller coaster
held to a looping track?

Section Problems

Section 0 - Introduction

0.1 Use the simulation in the interactive problem in this section to answer the following questions. (a) Is the centripetal

acceleration of the car higher when it is moving faster? (b) If the speed of the car remains constant, do the x and y

components of the car's velocity change as the car goes around the track?

(a) Yes No

(b) Yes No

Section 2 - Period

2.1 Jupiter's distance from the Sun is 7.78×10^11 meters and it takes 3.74×10^8 seconds to complete one revolution of the Sun in

its roughly circular orbit. What is Jupiter's speed?

m/s

2.2 Saturn travels at an average speed of 9.66×10^3 m/s around the Sun in a roughly circular orbit. Its distance from the Sun is
1.43×10^12 m. How long (in seconds) is a "year" on Saturn?
s

2.3 Mars travels at an average speed of 2.41×10^4 m/s around the Sun, and takes 5.94×10^7 s to complete one revolution. How far
is Mars from the Sun?
m

2.4 Long-playing vinyl records, still used by club DJs, are 12 inches in diameter and are played at 33 1/3 revolutions per minute.
What is the speed (in m/s) of a point on the edge on such a record?

m/s

Section 3 - Centripetal acceleration

3.1 A runner rounds a circular curve of radius 24.0 m at a constant speed of 5.25 m/s. What is the magnitude of the runner's
centripetal acceleration?
m/s^2

3.2 In a carnival ride, passengers are rotated at a constant speed in a seat at the end of a long horizontal arm. The arm is 8.30 m
long, and the period of rotation is 4.00 s. (a) What is the magnitude of the centripetal acceleration experienced by a rider? (b)
State the acceleration in "gee's," that is, as a multiple of the gravitational acceleration constant g.
(a) m/s^2
(b) g

3.3 Consider the radius of the Earth to be 6.38×10^6 m. What is the magnitude of the centripetal acceleration experienced by a

person (a) at the equator and (b) at the North Pole due to the Earth's rotation?

(a) m/s^2

(b) m/s^2

3.4 When tires are installed or reinstalled on a car, they are usually first balanced on a device that spins them to see if they
wobble. A tire with a radius of 0.380 m is rotated on a tire balancing device at exactly 460 revolutions per minute. A small
stone is embedded in the tread of the tire. What is the magnitude of the centripetal acceleration experienced by the stone?
m/s^2

3.5 A toy airplane connected by a guideline to the top of a flagpole flies in a circle at a constant speed. If the plane takes 4.5 s to

complete one loop, and the radius of the circular path is 11 m, what is the magnitude of the plane's centripetal acceleration?

m/s^2

Copyright 2007 Kinetic Books Co. Chapter 8 Problems^173