# Chapter 6 - Dynamics I: Motion Along a Line - Exercises and Problems - Page 155: 17

$\mu_k = 0.25$

#### Work Step by Step

Since the safe moves with a constant speed, the acceleration is zero. We can set up a force equation to find the coefficient of kinetic friction: $\sum F = ma$ $385~N+350~N-F_f = 0$ $mg~\mu_k = 385~N+350~N$ $\mu_k = \frac{735~N}{(300~kg)(9.80~m/s^2)}$ $\mu_k = 0.25$

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.