What is meant by positive work, negative work and zero works? Give examples of each type.

In physics, work is defined as the transfer of energy through force applied over a distance. It can be classified into three types: positive work, negative work, and zero work.

Positive Work:
Positive work occurs when the force applied to an object and the displacement of that object are in the same direction. This means that energy is being transferred to the object, causing it to move.

Example: When you push a box on the ground in the direction of the push, then the work done is positive since the force and the displacement are in the same direction.

Negative Work:
Negative work occurs when the force applied to an object and its displacement are in opposite directions. In this case, energy is being taken away from the object, slowing it down or causing it to lose energy.

Example: When brakes are applied to a moving car, the force exerted by brakes acts opposite to the direction of car motion. Work done by brakes will be negative since it decreases the kinetic energy of the car.

Zero Work:
This means zero work is when the displacement is in the direction of an applied force, or the displacement is perpendicular to the force. Thus, even if a force may be applied, no energy will have been transferred to the object in that direction.

For instance, when carrying a heavy bag at constant velocity while walking, the upward force applied by the hand to the bag does not contribute any work to the bag along the horizontal direction of travel. The displacement of the bag is perpendicular to the force due to gravity on the bag. If one exerts effort on pushing against a wall without causing the wall to budge, the work performed is zero.

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https://www.tiwariacademy.com/ncert-solutions/class-11/physics/chapter-5/