A particle of mass `m` collides with another stationary particle of mass `M` such that the second particle starts moving and the first particle stops just after the collision. Then which of the following conditions must always be valid ?

Options

A. 1
B. `m/M`
C. `(M-m)/(M+m)`
D. `m/(M+m)`

Answer

B

Explanation

As net horizontal force acting on the system is zero, hence, momentum must remain conserved.
Hence, `mu + 0 = 0 +Mv_(2)`
As per definition, `e = |(v_(2)-v_(1))|/|(u_(2)-u_(1))| = |(v_(2)-0)/(0-u)|`
`v_(2)/u= (mu)/(M)/u = m/M`