# Nature Of Work Done In Different Situations

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Work is a scalar quantity. It’s value may be positive, negative or even zero.

#### (I) Positive Work

If a force acting on a body has a component in the direction of the displacement, then the work done by the force is positive.

Example:- When a horse pulls a card, the applied force and the displacement are in the same direction. So, work done by horse is positive.

#### (II) Negative Work

If a force acting on a body has a component in the opposite direction of displacement, then work done is negative.

Example:- When a breaks are applied to a moving vehicle, the work done by the breaking force is negative, this is because the breaking force and the displacement act in opposite directions.

#### (III) Zero Work

Work done by force is zero, if the body gets displaced in the direction perpendicular to the direction of the applied force.

Example:- A body moving in a circle with constant speed. Every point of the circular path the centripetal force and the displacement are mutually perpendicular. So, the work done by centripetal force is zero.

Work Done W = FSCos90 = 0