At a construction site, a 65.0 bucket of concrete hangs from a light (but strong) cable that passes over a light friction-free pulley and is connected to an 85.0box on a horizontal roof (see the figure (Figure 1) ). The cable pulls horizontally on the box, and a 46.0 bag of gravel rests on top of the box. The coefficients of friction between the box and roof are shown. The system is not moving.Us=0.7Uk=0.4A. Find the friction force on the bag of gravel.Express your answer using two significant figures.B. Find the friction force on the box.C.Suddenly a worker picks up the bag of gravel. Use energy conservation to find the speed of the bucket after it has descended 1.80 , from rest. (You can check your answer by solving this problem using Newton’s laws.)