Question

A heavy steel ball of mass greater than 1kg moving with speed of 2 collide head on with a stationary ping-pong ball of mass less than 0.1 kg. The collision is elastic. After the collision the pingpong ball moves approximately with speed

Answer 1

by momentum conservation theorem,

M1V1 =M2V2

~1*2 = 0.1*V2

V2 =2*10=20 since unit has not been mentioned in the question therefore ....