Here's why:
* Work is defined as the force applied over a distance. Specifically, it's the product of the force and the displacement of the object in the direction of the force: Work (W) = Force (F) x Displacement (d).
* If there is no displacement, there is no work done. Imagine pushing against a wall. You're exerting force, but the wall isn't moving. Since there's no displacement, there's no work done.
* The force must be in the direction of the displacement. If you lift a box straight up, you do work because the force you exert (upwards) is in the direction of the displacement (upwards). However, if you carry the box horizontally, you might be exerting force to keep it from falling, but no work is being done because the displacement is perpendicular to the force.
Examples:
* Work done: Pushing a grocery cart down an aisle (force applied in the direction of movement).
* No work done: Holding a heavy weight stationary (force applied but no movement).
Let me know if you have any other physics questions!
