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Question
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
Solution
Yes, it is possible that a force is acting on a body but the work done is still zero. Following are the cases:
1. The displacement is zero.
2. The force and displacement are perpendicular to each other.
We know,
W = (F) (S) cos θ
Where,
(W) - Work done
(F) - Force
(S) - Displacement
(θ ) - Angle between force and displacement
From the equation itself, when the displacement is zero the work done is zero.
Example: No work is done when one pushes a wall that remains static even after pushing very hard.
When the force is perpendicular to the direction of motion, , and hence the work done is also zero.
Example - Work done by the force of gravity on a horizontally moving body is zero, because the force of gravity is perpendicular to the horizontal.
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