An angler hangs a 4.50 kg fish from a vertical steel wire 1.50 m long and 5.00 * 10-3 cm2 in cross-sectional area. The upper end of the wire is securely fastened to a support. (a) Calculate the amount the wire is stretched by the hanging fish. The angler now applies a varying force F at the lower end of the wire, pulling it very slowly downward by 0.500 mm from its equilibrium position. For this downward motion, calculate (b) the work done by gravity; (c) the work done by the force F S ; (d) the work done by the force the wire exerts on the fish; and (e) the change in the elastic potential energy (the potential energy associated with the tensile stress in the wire). Compare the answers in parts (d) and (e).

(25) A biomechanical model of the bones and biceps muscles of a person's arm supporting a mass m=2 kg is shown below. The weight of the forearm is 9 N. If the cross section of the tendon AB is 28 mm' what is the average normal stress in the tendon? 4f 290 mm r OS 150 mm 200 mm

A rigid bar of mass M is supported symmetrically by three wires each of length l. Those at each end are ofcopper and the middle one is of iron. The ratio of their diameter, if each is to have the same tension, is equal to (a)YcopperYiron(b) √YironY copper(c)Yiron2Ycopper2(d)YironYcopper