Describe situations where no work is done and situations where work would be done?

To describe situations where no work is done and situations where work would be done, we need to understand the concept of work in physics.

In physics, work is defined as the transfer of energy that occurs when a force is applied to an object and that object is displaced in the direction of the force. Mathematically, work is calculated as the product of the force applied to an object and the displacement of that object in the direction of the force.

Now, let's consider some situations:

1. No work is done:
- If a person pushes against a wall but the wall does not move, no work is done. This is because there is no displacement of the wall in the direction of the force applied. Therefore, even though force is applied, there is no work done.
- Similarly, if you hold a heavy object and walk horizontally without changing the height of the object, no work is done. In this case, the force you apply is in the horizontal direction, but the displacement of the object is vertical. As the displacement is perpendicular to the force, no work is done.

2. Work is done:
- If you lift a book from the ground and place it on a shelf, work is done in this situation. This is because you are applying a vertical force to the book, and the book is displaced vertically against the force applied. As there is displacement in the direction of the force, work is done.
- When a car accelerates along a road, work is done by the car's engine. The force applied by the engine causes a displacement of the car in the same direction as the force, resulting in work being done.

To determine whether work is done in a particular situation, it is essential to consider both the application of force and the displacement of the object in the direction of the force.