Question

Chapter 07, Problem 38 GO A ball is attached to one end of a wire, the other end being fastened to the ceiling. The wire is held horizontal, and the ball is released from rest (see the drawing). It swings downward and strikes a block initially at rest on a horizontal frictionless surface. Air resistance is negligible, and the collision is elastic. The masses of the ball and block are, respectively, 1.7 kg and 2.5 kg, and the length of the wire is 1.39 m. Find the velocity (magnitude and direction) of the ball (a) just before the collision, and (b) just after the collision. (a) v = (b) v ol

Answer 1

solution) m = 1.7kg M = 2.5kg l=)-39m (a) Vo = ? (just before Collision) from Conservation of energy I PE = k E = mg l = ₃ mo. - 2 = 2gl verage v = 82 x 9.8 x 1.39 = siz1a mis = 5.22mis (approximately + x-aris right] direction v=s.2] mis Collision) Collision, both momentum are conferred. V = ? (just after As Collision is elastic and kinetic energy Collision, (2 m2 In elastic iam, final I m, + M2 velocity = o( block is at rest) of first? object) here V, = vf Imam com v. + 0 = (012 2,5)(-2) [/f = -0.9904)mls [if = -0.971 m/s approsinately 1 Vf = -0.99 mis direction is -x-ares) [left taken as f Can be [ Vf = -1} mis