There object `A ,B` and `C` are kept is a straing line a fritionlas horizental surface . These have masses have increase on `2m` and `m` repectively . The object `A` move toward `B` with a speed `9` m//s and makes as electic collision with a there after `B` makes complately inclesis with `C` . All motion over on the same strangth line . Find the first speed of the object `C`

Answer

D

Explanation

The velocity `B` just after collision with `A` is
`v_(g) = ((mg - m_(A) ) u g )/(mg + m _(A) ) + (2m_(A) u_(A))/(m_(A) + mg)`

`= (0 + 2m xx 9)/(m + 2m) = 6m//s`
The collision between `B` and `C` is completely inedasic
`:. m_(g) nu_(g) = (m_(g) + m_(C) ) nu`
`:. nu = (6 xx 2m)/(2m + m) = 4 m//s`