Question

Give an example when work done by the force of gravity acting on a body is zero even though the body gets displaced from its initial position.

April 8, 2024

Answer

When a coolie carrying a load moves on a horizontal platform, the force of gravity acting on him is normal to the displacement of the load i.e. the angle between force and displacement of load is 90°.

Work done by Coolie = F × S Cos 90° = F x S x 0 = 0.

Therefore, in this case work done by the force of gravity is zero even though the load gets displaced from its initial position.

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(b) What is the total mechanical energy at point C?
(c) What is the speed of the bob at position A when released from position B ? (Take g = 10 ms^-2)

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The bob of a simple pendulum is imparted a velocity of 5 m s^-1 when it is at its mean position. To what maximum vertical height will it rise on reaching at its extreme position if 60% of its energy is lost in overcoming the friction of air? (Take g = 10 m s^-2).

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Question

Give an example when work done by the force of gravity acting on a body is zero even though the body gets displaced from its initial position.

Answer

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