A body of mass `20 gm` is moving with a certain velocity. It collides with another body of mass `80 gm` at rest. The collision is perfectly inelastic. The ratio of the kinetic energies before and after collision of the system is

Options

A. `2 : 1`
B. `4 : 1`
C. `5 : 1`
D. `3 : 2`

Answer

C

Explanation

`m_(1) u_(2) = (m_(1) + m_(2)) v`
`KE_(i) = (1)/(2) m_(1)u_(1)^(2) , KE_(f) = (1)/(2) (m_(1) +m_(2)) v^(2)`.