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Theory:

In this section, we will discuss Positive and Negative work with an example.
 
Let us consider,
 
When the object is lifted. the force exerted by you is used to do the work. When the object moves upwards, you exert force in the same line of direction of displacement.
 
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Lifting a rock
 
Still, there is the force of gravity acting on the object.
  • Which one of these forces is doing Positive work?
  • Which one is doing Negative work?
Positive work:
When force and displacement are in the same direction, the work performed on an object is said to be positive work.
Negative work:
Negative work is performed if the displacement is opposite to the direction of the force applied.
In this example,
  • Work done by an external force is positive as the displacement takes place in the direction of the force.
  • Work done by the gravitational force is negative as gravity is acting downward and displacement is upward.