## College Physics (4th Edition)

We can see the free body diagram below. Note that the box represents the system of ropes, pulleys, and the engine. Let upward be the positive direction. We can find the net force: $\sum F_y = T_C+T_B-W-T_C$ $\sum F_y = 902.0~N+1804~N-1804~N-902.0~N$ $\sum F_y = 0$ The net force exerted on the system is zero.