Question

Once a 22 kg crate is in motion on a horizontal floor, a horizontal force of 52 n keeps the crate moving with a constant velocity. the acceleration of gravity is 9.81 m/s 2 . what is µk, the coefficient of kinetic friction, between the crate and the floor?

Answer 1

ÎĽk= Ff/Fn   
Fn = m x g = 25 x 9.81 = 245.25N 
 Since the crate is moving with a constant velocity, it is neither speeding up nor slowing down, so the Fa = Ff so 52N = 52N. Therefore: 
 Ff = 52N  
 ÎĽk= Ff/Fn 
 = 52N/245.25N  
= 0.212