A 92 kg clock initially at rest on a horizontal floor requires a 656 N horizontal force to set it in motion. After the clock is in motion, a horizontal force of 560 N keeps it moving with a constant speed.

1 answer

Wc = M*g = 92kg * 9.8N/kg = 902 N. =
wt. of the clock.

Fap-Fs = M*a
656 - Fs = M*0 = 0
Fs = 656 N. = Force of static friction.

us = Fap/Wc = 656/902 = 0.727

uk = 560/902 = 0.621