1. The problem statement, all variables and given/known data A crate of potatoes of mass 13.0 kg is on a ramp with angle of incline 40° to the horizontal. The coefficients of friction are μs = 0.78 and μk = 0.43. Find the frictional force (magnitude) on the crate if the crate is at rest. 2. Relevant equations F=ma Ff=μmgcosα 3. The attempt at a solution Ff=.78*13*9.81*cos40 =76.2 N Why is my answer wrong?