Work is done when a force causes a displacement of an object.

More specifically:

* Force: A push or pull that can change the motion of an object.

* Displacement: The change in an object's position.

Mathematically, work is defined as:

Work (W) = Force (F) × Displacement (d) × cos(θ)

Where:

* θ is the angle between the force and the displacement.

Key points:

* Work is a scalar quantity: It has magnitude but no direction.

* Work is measured in Joules (J): 1 Joule is equal to 1 Newton-meter (N⋅m).

* Work is only done if there is both a force and a displacement. For example, if you push on a wall but it doesn't move, you have done no work.

* The direction of the force and displacement are important. If the force and displacement are in the same direction, the work is positive. If they are in opposite directions, the work is negative. If they are perpendicular, the work is zero.

Examples:

* Lifting a box: You apply a force upward, and the box moves upward, so you do positive work.

* Pushing a car: You apply a force forward, and the car moves forward, so you do positive work.

* Holding a heavy weight: You apply a force upward, but the weight doesn't move, so you do no work.

It's important to note that the scientific definition of work may differ from the everyday usage of the word "work". In everyday language, "work" can refer to any activity, whether or not it involves a force and displacement.