Problem

(a) What minimum force F is needed to lift the piano (mass M) using the pulley apparatus shown in Fig. 4—66? (b) Determine the tension in each section of rope: FT1, FT2 , FT3 and FT4 Assume pulleys are massless and frictionless, and that ropes are massless.

Solution 78GP: In the first part, we have to derive the relation between the minimum applied force F in terms of mass of the piano M , while in the second part we have to derive the relation between the tensions in various part of the rope. Step 1 of 3 Concept: Newton’s second law: The net force F acting on an object of mass m produces an acceleration a in that object. Mathematically, F= ma. Tension is the internal developed in the rope, which depends upon the application and magnitude of force applied. Free body diagram of a body gives the diagrammatical representation of all the forces acting on the body in terms of magnitude and diagram, under the given situation.