Question 18

In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.

Answer

Work is done whenever the given conditions are satisfied:

(i) Force is applied.

(ii) Displacement takes place.

(iii) The angle between the force and displacement is not 90 degrees .

*Case I*

In this case, the angle between the force and displacement is 90 degrees. Hence, work done by force on the block will be zero.

*Case II*

In this case, the angle between the force and displacement is 0 degree. Hence, work done by force on the block will be positive.

*Case III*

In this case, the angle between the force and displacement is 180 degrees. Hence, work done by force on the block will be negative.

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- NCERT Chapter

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