The impact is perfectly elastic

Question

A small ball of mass 1 kg moving with a velocity of 12 m/s undergoes a direct central impact with a stationary ball of mass 2 kg. The impact is perfectly elastic. The speed (in m/s) of 2 kg mass ball after the impact will be __________________

Answer 1

$\therefore$ Velocity of the 2kg mass ball after the impact is 8 m/sec