Question

Two balls of clay are shot at each other with an initial angle of 110 degrees between them. One ball has a mass of 30 g and a speed of 1.5 m/s, and the other ball has a mass of 40 g and a speed of 1.2 m/s. When the balls collide, they stick together. What is the velocity (speed and direction) of the 70-g ball after the collision?

Answer 1

As we know in the absence of any external force, linear momentum of the system remains conserved, so-

initial momentum = final momentum

if first ball is travelling in x direction then velocity vector of second will be given by -

initial momentum of ball 1 = 30*1.5 i = 45 i

initial momentum of ball 2 = 40*1.2 [cos 110 i + sin 110 j] = 48[- 0.34 i + 0.94 j ]

total initial momentum = - 16.32 i + 45.12 j + 45 i = 28.8 i + 45.12 j

final momentum = 70 v

70 v = 28.8 i + 45.12 j

v = 0.41 i + 0.64 j