A man weighing 60 kg is standing on a trolley weighing 240 kg. The trolley is resting on frict

step 1 Here we have a man who is standing on a trolley and he starts walking on the trolley with speed

A man weighing 60 kg is standing on a trolley weighing 240...

A man weighing $60 \mathrm{~kg}$ is standing on a trolley weighing $240 \mathrm{~kg}$. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a velocity of $1 \mathrm{~ms}^{-1}$, then after $4 \mathrm{~s}$, his displacement relative to the ground is (a) $6 \mathrm{~m}$ (b) $4.8 \mathrm{~m}$ (c) $3.2 \mathrm{~m}$ (d) $2.4 \mathrm{~m}$

A man weighing $60 \mathrm{~kg}$ is standing on a trolley weighing $240 \mathrm{~kg}$. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a velocity of $1 \mathrm{~ms}^{-1}$, then after $4 \mathrm{~s}$, his displacement relative to the ground is
(a) $6 \mathrm{~m}$
(b) $4.8 \mathrm{~m}$
(c) $3.2 \mathrm{~m}$
(d) $2.4 \mathrm{~m}$

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Key Concepts

Conservation of Momentum

In a frictionless system with no external horizontal forces, the total momentum remains conserved. When the man starts walking, his forward momentum is balanced by the backward momentum of the trolley. This principle helps in determining the velocities of both the man and the trolley relative to the ground.

Relative Velocity

Relative velocity is the rate at which one object moves with respect to another. In this problem, the man's walking speed is provided relative to the trolley, so it is necessary to combine his velocity relative to the trolley with the trolley’s velocity relative to the ground to find his overall displacement.

Reference Frames

The concept of reference frames involves analyzing motion from different perspectives. The problem requires switching from the trolley’s frame, where the man’s speed is given, to the ground frame, where his displacement is to be determined. Understanding how motion transforms between these frames is key to solving the problem.

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