Question

Draw the free body diagram.

Answer 1

Hint: To draw the free body diagram we have to resolve the forces in the system. If the system is in equilibrium then the net force on the body is zero. From this it can be implied that there exists no relative motion in the system at equilibrium.

Complete answer:
To begin with let us first understand what does free body diagram mean. A free body diagram gives the action of various forces of the individual body in a given system. Once we have a free body diagram of a body in a system, we can analyze the body separately as if the other bodies aren’t there in the system. To draw the free body diagram of the above pulley system let us assume all the pulleys are massless and frictionless. Also let us say that the system is stationary. The action of T results in a tension in the rope such that the system remains in equilibrium and tension is equal to T.
Tension along the same rope remains constant as the ropes are massless. The rope along the pulley ‘C’ will have tension T. One of the ends of the rope is attached of pulley B, hence the tension of the rope of the attached section will also be T. As a result The rope along pulley A will have a tension of2T i.e. of its free end and its attached end. Therefore the rope tied to the weight of 1000lbs will have a net tension of 4T. therefore our free body diagram becomes,

Note:
It is to be noted that the system is in equilibrium. Hence there is no net force on the body of weight 1000lbs. It is also to be noted that tension is always a pulling force and it cannot do the work of pushing.