Center of Mass, Momentum & Collision

JEE Main level, numerical answer, medium

15 of 130

Question 15 of 130

A man of 60kg60kg is running on the road and suddenly jumps into a stationary trolly car of mass 120kg120kg. Then the trolly car starts moving with velocity 2ms−12{ms}^{-1}. The velocity of the running man was _____ ms−1m{s}^{-1}, when he jumps into the car.

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Answer: 6

Applying conservation of the momentum,
mmu=(mm+mt)v⇒60u=(60+120)×2⇒u=6ms−1{m}_{m}u=\left({m}_{m}+{m}_{t}\right)v\Rightarrow 60u=\left(60+120\right)\times 2\Rightarrow u=6m{s}^{-1}

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