Question

A cue ball with mass 170 g hits the stationary number 8 ball, which has mass 160 g. The cue ball and the 8 ball move with a speed of 0.2 m/s and 0.3 m/s respectively after the collision. What was the speed of the cue ball before the collision?

Answer 1

applying momentum conservation

$P_i=P_f$

$170\times v=170\times0.2+160\times0.3=34+48=82$

v=0.48m/s