A ball with mass M, moving horizontally at 4.00 m/s, collides elastically with a block with mass 3 M that is initially hanging at rest from the ceiling on the end of a 50.0-cm wire. Find the maximum angle through which the block swings after it is hit.

Solution 87 P Step 1: Data given Velocity of the ball v = 4.0 m/s Mass of ball m =1M Mass of block m =23M Height along z axis 50 .0 cm We need to find the angle of the swing after the collision Since its an elastic collision we shall find the initial velocity of the swing and final velocity of the swing after collision Using the law of conservation we have M × 4 + 0 = M × v + 3M × u Here v final velocity and u initial velocity M × 4 M × v = 3M × u Removing all the M terms we have 4 v = 3u This can re written as 3u + v = 4 Since we have elastic collision e=1 Hence we get u v = 4 Thus we have v = 2m/s and u = 2 m/s