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Four identical railway wagons each of m,...

Four identical railway wagons each of m, are coupled together and rest on a smooth horizontal track. A fifth wagon of mass 2m and movingk at 5m/s collides and couple with the statioinary wagons. What is the speed of the wagons after the impact?

A

`5/6m//s`

B

`1 m//s`

C

`5/4 m//s`

D

`5/3m//s`

Text Solution

Verified by Experts

The correct Answer is:
D
Linear momentum of A.
`P_x=5times2=10kgm//s` along x-axis
Linear momentum of B,
`P_y=10timessqrt3=10sqrt3kgm//s` along y-axis
`therefore` Resultant initial momentum
`=sqrt(P_x^2+P_y^2)=sqrt(10^2+(10sqrt3)^2)=20kgm//s`
`therefore` From the principle of conservation of linear momentum, 20 =15v
`thereforev=20/15=4/3m//s`
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