1. The problem statement, all variables and given/known data A horizontal force of 150 N is used to push a 50.0 kg packing crate a distance of 5.00 m on a rough horizontal surface. The acceleration of gravity is 9.81 m/s2 . If the crate moves with constant velocity, calculate: a) the work done by the force. Answer in units of J. b) the coefficient of kinetic friction. 2. Relevant equations W=Fdcostheta Ff=muFn 3. The attempt at a solution I got part a right. However I am struggling for part B. Here is my work for both parts... a) W=fdcostheta W=(150)(5)cos(0) W=750J b) Ff=muFn Fn=Fg Fn= 50*9.81=490.5N Ff=0 because there is constant velocity. Therefore, mu=0. This answer is wrong. Can anyone tell me where I went wrong. Thank you.