posted by Ricky on .
A dockworker loading crates on a ship finds that a 19-kg crate, initially at rest on a horizontal surface, requires a 70-N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 60 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.
Take a look at the definitions of the friction coefficients. That should tell you how to do this problem, which is:
Divide the required forces by the weight. Use 70 N for the static coefficient, and 60 N for the kinetic one.