Here's why:
* Work is defined as the force applied multiplied by the distance moved in the direction of the force.
* Displacement is the overall change in position, measured as a straight line from the starting point to the ending point.
Examples:
* Pushing against a wall: You exert force on the wall, but it doesn't move. The displacement is zero, so no work is done.
* Holding a heavy object: You exert force to keep the object from falling, but it doesn't move. The displacement is zero, so no work is done.
* A car parked on a hill: Gravity exerts a force on the car, but it doesn't move. The displacement is zero, so no work is done.
Important Note: Even though no work is done, the force can still have an effect. For example, pushing against a wall may create a feeling of strain in your muscles, or holding a heavy object may cause fatigue. These effects are related to energy expenditure and not work done in the physics sense.
