A man of mass \(100 \,kg\). is standing on a platform of mass \(200 \,kg\). Which is kept on a smooth ice surface. If the man starts moving on the platform with a speed \(30 \,m/sec\) relative to the platform then calculate with what velocity relative to the ice the platform will recoil?
- 5 m/sec
- 10 m/sec
- 15 m/sec
- 20 m/sec
The Correct Option is B
Solution and Explanation
Then the man is moving wrt the ice in the opposite direction at (30-V) velocity. Recoil velocity V = 10 m/s in the opposite direction of movement of the man.
100 * (30-V) - 200 * V = 0
300 V = 3000
Velocity of the man wrt to ice = 20m/s
(Their relative velocity = 30 m/s)
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Concepts Used:
Center of Mass
The center of mass of a body or system of a particle is defined as a point where the whole of the mass of the body or all the masses of a set of particles appeared to be concentrated.
The formula for the Centre of Mass:
Center of Gravity
The imaginary point through which on an object or a system, the force of Gravity is acted upon is known as the Centre of Gravity of that system. Usually, it is assumed while doing mechanical problems that the gravitational field is uniform which means that the Centre of Gravity and the Centre of Mass is at the same position.