Question

A body is moved in a direction opposite to the direction of force acting on it. State whether the work is done by the force or work is done against the force.

April 8, 2024

Answer

When a body is moved in a direction opposite to the direction of force then work is done against the force acting on the body.

When the displacement of the body due to the application of force is in a direction opposite to the force then,

θ = 180°, and

cos 180° = -1

Therefore, Work done = (-) Force x displacement of the body.

💡 Some Related Questions

The figure alongside shows a simple pendulum of mass 200 g. It is displaced from the mean position A to the extreme position B. The potential energy at position A is zero. At position B the bob is raised by 5 m.
(a) What is the potential energy of the pendulum at position B ?
(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)

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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(a) Calculate the change in the gravitational potential energy of the skier between A and B.
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(Take g = 10 ms^-2).

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(c) What happens to the mechanical energy after the ball hits the ground and comes to rest?

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Name the type of energy possessed by the bob of a simple pendulum when it is at
(a) the extreme position,
(b) the mean position, and
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