A body of mass `m_(1) ` moving with uniform velocity of 40 m/s collides with another mass `m_(2)` at rest and then the two together begin to moe wit h uniform velocity of 30 m/s. the ratio of their masses `(m_(1))/(m_(2))` is

Options

A. `1:3`
B. `3:1`
C. `1:1.33`
D. `1: 0.75`

Answer

B

Explanation

(b) Initial momentum of the sytem
`=m_(1) xx 40 + m_(2) xx 0 = 40m_(1)`
Final momentum of the system.
`=m_(1) xx 40 + m_(2) xx 0 = 40m_(1)`
Final momentumof the system,
`=(m_(1) + m_(2)) xx 30` ltbrlt By law of conservation of momentum,
Initial momentum = Final momentum
`40m_(1) = ((m_(1) + m_(2))30`
`40m_(1) - 30m_(1) = 30m_(2)`
`10m_(1) = 30m_(2)`
`m_(1)/m_(2) = 3/`