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A body of mass m moving with velocity 3k...

A body of mass m moving with velocity `3km//h` collides with a body of mass 2m at rest. Now, the coalesced mass starts to move with a velocity

A

3 km/hour

B

4 km/hour

C

1 km/hour

D

2 km/hour

Text Solution

Verified by Experts

The correct Answer is:
C
Mass of body `(m_(1)) = m`
Velocity of first body `(mu_(1)) = 3` km/hour
Mass of second body in rest `(m_(2))= 2m`
Velocity of second body `(u_(2)) =0`
After combination, mass of the body `(M) = m + 2m = 3m`
From the law of conservation of momentum, we get,
Mv `=m_(1)u_(1) + m_(2)u_(2)`
or `3mv = (m xx 3) + (2m xx 0) = 3m`
or v=1 km/hour.
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