At a construction site, a 66.0 kg bucket of concrete hangs from a light (but strong) cable that passes over a light friction-free pulley and is connected to an 83.0 kg box on a horizontal roof (see the figure ). The cable pulls horizontally on the box, and a 48.0 kg 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.
Find the friction force on the bag of gravel.
Suddenly a worker picks up the bag of gravel. Use energy conservation to find the speed of the bucket after it has descended 2.10 m , from rest. (You can check your answer by solving this problem using Newtons laws.)
Find the friction force on the box.
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