A dockworker loading crates on a ship finds that a 19-kg crate, initially at rest on a horizontal surface, requires a 83-N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 53 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.

1 answer

Wc = m*g = 19kg * 9.8N/kg = 186.2 N. =
Weight of crate.

Fap-Fs = m*a
83-u*mg = m*0
83-u*186.2 = 0
186.2u = 83
us = 0.446

uk*186.2 = 53
uk = 0.285