The Physics of Everyday Phenomena
The Physics of Everyday Phenomena
8th Edition
ISBN: 9780073513904
Author: W. Thomas Griffith, Juliet Brosing Professor
Publisher: McGraw-Hill Education
Question
Book Icon
Chapter 8, Problem 1SP

(a)

To determine

The net torque acting on the merry-go-round about its axle.

(a)

Expert Solution
Check Mark

Answer to Problem 1SP

The net torque acting on the merry-go-round about its axle is 132 Nm.

Explanation of Solution

Given info: The radius of the merry-go-round is 1.8 m. The rotational inertia is 900 kgm2. The force applied is 80 N and the frictional torque of the axle of the merry-go-round is 12 Nm.

Write the expression to find the torque acting due to the force.

τ=Fl

Here,

F is the applied force

l is the radius of the merry-go-round

Substitute 80 N for F and 1.8 m for l in the above equation.

τ=(80 N)(1.8 m)=144 Nm

Write the expression to find the net torque acting on the axle of the merry-go-round.

τnet=ττf

Here,

τ is the torque due to the force

τf is the frictional torque at the axle

Substitute 144 Nm for τ and 12 Nm for τf in the above equation.

τnet=144 Nm12 Nm=132 Nm

Conclusion:

Therefore, the net torque acting on the merry-go-round about its axle is 132 Nm.

(b)

To determine

The rotational acceleration of the merry-go-round.

(b)

Expert Solution
Check Mark

Answer to Problem 1SP

The rotational acceleration of the merry-go-round is 0.147 rad/s2.

Explanation of Solution

Write the expression to find the rotational acceleration of the merry-go-round.

α=τI

Here,

α is the rotational acceleration

τ is the torque

I is the rotational inertia

Substitute 132 Nm for τ and 900 kgm2 for I in the above equation.

α=132 Nm900 kgm2=0.147 rad/s2

Conclusion:

Therefore, the rotational acceleration of the merry-go-round is 0.147 rad/s2.

(c)

To determine

The rotational velocity of the merry-go-round after 15 s if it starts from rest.

(c)

Expert Solution
Check Mark

Answer to Problem 1SP

The rotational velocity of the merry-go-round after 15 s if it starts from rest is 2.2 rad/s.

Explanation of Solution

Write the expression to find the rotational velocity of the merry-go-round.

ω=αt

Here,

α is the rotational acceleration

ω is the rotational velocity

t is the time taken

Substitute 0.147 rad/s2 for α and 15 s for t in the above equation.

ω=(0.147 rad/s2)(15 s)=2.2 rad/s

Conclusion:

Therefore, the rotational velocity of the merry-go-round after 15 s if it starts from rest is 2.2 rad/s.

(d)

To determine

The rotational acceleration of the merry-go-round after the child stops pushing after 15 s and the time taken for the merry-go-round to stop turning.

(d)

Expert Solution
Check Mark

Answer to Problem 1SP

The rotational acceleration of the merry-go-round after the child stops pushing after 15 s is 1.3×102 rad/s2 and the time taken for the merry-go-round to stop turning is 165 s.

Explanation of Solution

Write the expression for rotational acceleration of the merry-go-round after the child stops pushing.

α=τfI

Substitute 12 Nm for τf and 900 kgm2 for I in the above equation.

α=12 Nm900 kgm2=1.3×102 rad/s2

Write the expression to find the time taken for the merry-go-round to stop turning.

t=ωα

Substitute 1.3×102 rad/s2 for α and 2.2 rad/s for ω in the above equation.

t=2.2 rad/s1.3×102 rad/s2=165 s

Conclusion:

Therefore, the rotational acceleration of the merry-go-round after the child stops pushing after 15 s is 1.3×102 rad/s2 and the time taken for the merry-go-round to stop turning is 165 s.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
When current is flowing through the coil, the direction of the torque can be thought of in two ways. Either as the result of the forces on current carrying wires, or as a magnetic dipole moment trying to line up with an external field (e.g. like a compass). Note: the magnetic moment of a coil points in the direction of the coil's magnetic field at the center of the coil. d) Forces: We can consider the left-most piece of the loop (labeled ○) as a short segment of straight wire carrying current directly out of the page at us. Similarly, we can consider the right-most piece of the loop (labeled ) as a short segment straight wire carrying current directly into the page, away from us. Add to the picture below the two forces due to the external magnetic field acting on these two segments. Then describe how these two forces give a torque and determine if the torque acts to rotate the loop clockwise or counterclockwise according to this picture? B
In each of the following, solve the problem stated. Express your answers in three significant figures. No unit is considered incorrect. 1. For the circuit shown, determine all the currents in each branch using Kirchhoff's Laws. (3 points) 6 5V 2 B C 4 A www 6 VT ww T10 V F E 2. Compute for the total power dissipation of the circuit in previous item. (1 point) 3. Use Maxwell's Mesh to find Ix and VAB for the circuit shown. (3 points) Ix 50 V 20 ww 21x B 4. Calculate all the currents in each branch using Maxwell's Mesh for the circuit shown. (3 points) www 5ი 10 24V 2A 2002 36V
If the mass of substance (1 kg), initial temperature (125˚C), the final temperature (175˚C) and the total volume of a closed container (1 m3) remains constant in two experiments, but one experiment is done with water ( ) and the other is done with nitrogen ( ). What is the difference in the change in pressure between water and nitrogen?

Chapter 8 Solutions

The Physics of Everyday Phenomena

Ch. 8 - The two forces in the diagram have the same...Ch. 8 - Is it possible to balance two objects of different...Ch. 8 - Is it possible for the net force acting on an...Ch. 8 - You are trying to move a large rock using a steel...Ch. 8 - Prob. 15CQCh. 8 - Prob. 16CQCh. 8 - Prob. 17CQCh. 8 - An object is rotating with a constant rotational...Ch. 8 - A tall crate has a higher center of gravity than a...Ch. 8 - Two objects have the same total mass, but object A...Ch. 8 - Is it possible for two objects with the same mass...Ch. 8 - Can you change your rotational inertia about a...Ch. 8 - A solid sphere and a hollow sphere made from...Ch. 8 - Is angular momentum always conserved? Explain.Ch. 8 - A metal rod is rotated first about an axis through...Ch. 8 - A child on a freely rotating merry-go-round moves...Ch. 8 - Moving straight inward, a large child jumps onto a...Ch. 8 - Is it possible for an ice skater to change his...Ch. 8 - Suppose you are rotating a ball attached to a...Ch. 8 - Does the direction of the angular-momentum vector...Ch. 8 - Does the direction of the angular momentum vector...Ch. 8 - Can a yo-yo be made to sleep if the string is tied...Ch. 8 - An ice skater is spinning counterclockwise about a...Ch. 8 - A pencil, balanced vertically on its eraser, falls...Ch. 8 - A top falls over quickly if it is not spinning,...Ch. 8 - When we shift gears on the rear-wheel gear of a...Ch. 8 - In what foot position do we exert maximum torque...Ch. 8 - If we move the chain to a larger sprocket on the...Ch. 8 - Prob. 1ECh. 8 - Prob. 2ECh. 8 - Prob. 3ECh. 8 - Prob. 4ECh. 8 - Prob. 5ECh. 8 - Prob. 6ECh. 8 - Prob. 7ECh. 8 - Prob. 8ECh. 8 - Prob. 9ECh. 8 - Prob. 10ECh. 8 - Prob. 11ECh. 8 - Prob. 12ECh. 8 - Prob. 13ECh. 8 - Prob. 14ECh. 8 - Prob. 15ECh. 8 - Prob. 16ECh. 8 - Prob. 17ECh. 8 - Prob. 18ECh. 8 - Prob. 1SPCh. 8 - Prob. 2SPCh. 8 - Prob. 3SPCh. 8 - Prob. 4SP
Knowledge Booster
Background pattern image
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
College Physics
Physics
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Cengage Learning
Text book image
University Physics (14th Edition)
Physics
ISBN:9780133969290
Author:Hugh D. Young, Roger A. Freedman
Publisher:PEARSON
Text book image
Introduction To Quantum Mechanics
Physics
ISBN:9781107189638
Author:Griffiths, David J., Schroeter, Darrell F.
Publisher:Cambridge University Press
Text book image
Physics for Scientists and Engineers
Physics
ISBN:9781337553278
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
Text book image
Lecture- Tutorials for Introductory Astronomy
Physics
ISBN:9780321820464
Author:Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina Brissenden
Publisher:Addison-Wesley
Text book image
College Physics: A Strategic Approach (4th Editio...
Physics
ISBN:9780134609034
Author:Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher:PEARSON