Lifting an object involves doing work because you're exerting a force that causes the object to move upward. Your applied force and the displacement are in the same direction, even though gravity continues to act downward on the object.
Lifting a rock
- Which one of these forces is doing Positive work?
- Which one is doing Negative work?
Work done is negative when the force acts
Work done is positive when the force is
In this example,
Work done by an external force is
Work done by the gravitational force is
For more detailed solution refer to the given link: Positive and negative work