A ball of mass 100g moving at a speed of 12 m `s^(-1)` strikes another ball of mass 200 g at rest. After the collision both the balls stick to each other and move with a common velocity. Find the common velocity.

Explanation

Let the common velocity of the two bodies be 'v'.
`{:(ul("1")"st " ul("ball"),ul(2)"nd "ul("ball")),(m_(1) = 100 g,m_(2) = 200 g),(u_(1) = 12 m s^(-1),u_(2) = 0 m s^(-1)),(v_(1) = v = ?,v_(2) = v = ?):}`
From law of conservation of momentum,
`m_(1)u_(1) + m_(2)u_(2) = m_(1)v_(1)+m_(2)v_(2)`
`100 xx 12 + 0 = 100 xx v + 200 xx v`
1200 = 300 v
`implies v = (1200)/(300) = 4 m s^(-1)`