Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

Published by Pearson
ISBN 10: 0133942651
ISBN 13: 978-0-13394-265-1

Chapter 7 - Newton's Third Law - Exercises and Problems: 45

Answer

The painter should pull down on the rope with a force of 400 N.

Work Step by Step

Let's consider the system of the painter and chair. Note that when the painter pulls down with a force $F$, the tension $T$ in the rope is equal in magnitude to the force $F$. Also note that the tension $T$ pulls up on the painter's hands, and the tension $T$ pulls up on the chair. To find the tension $T$, we can set up a force equation for the system of the painter and chair. Let $M$ be the total mass of the system. So; $\sum F = Ma$ $T+T-Mg = Ma$ $2T = M(g+a)$ $T = \frac{M(g+a)}{2}$ $T = \frac{(70~kg+10~kg)(9.80~m/s^2+0.20~m/s^2)}{2}$ $T = 400~N$ Since the force $F$ is equal in magnitude to $T$, the painter should pull down on the rope with a force of 400 N.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.