A particle of mass `m_(1)` moving on a smooth surface with some velocity strikes another particle of mass `m_(2)` at rest. The head - on elastic collision takes place. After the collision , particles move with equal speed in opposite direction . Determine the mass ratio.

Explanation

By the momentum conservation
`m_(1) u + m_(2) xx 0 = -m_(1) v + m_(2) v` (i)
` - v + u = v + 0` (ii)
From (ii) , `v = (u)/(2)` in (i)
`m_(1) u = (-m_(1) + m_(2)) (u)/(2)`
`2m_(1) = -m_(1) + m_(2)`
`(m_(1))/(m_(2)) = (1)/(3)`