A Fletcher's trolley is set up over a cliff. If m1 = 40.5 kg (on top of the cliff) and m2 = 18.5 kg (hanging over the edge), what coefficient of friction is needed for the system not to move?

m2*g = m1*g*mu_s

mu_s is the required minimum static coeficient of friction.

mu_s = m2/m1 = 0.457