Give condition for no work.

1.	Give condition for no work.
Answer» \tWhen the force acts in a direction at right angle to the direction of displacement (cos90° = 0), no work is done (zero work).\tWork done by the force is negative if the angle between force and displacement is obtuse (90°<θ<180°) as cosθ is negative. This signifies, when the force and displacement are in opposite direction, work done is negative. This work is said to be done by the body.

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