In everyday language, we describe many activities as "work"—studying for exams, carrying groceries, or holding a heavy box. However, physicists define work more precisely: work is the energy transferred into or out of a system when a force acts on an object as it moves through a distance.

For a constant force acting parallel to the displacement, the work done is:

where $F$ is the magnitude of the force, $d$ is the magnitude of the displacement, and both are measured in the same direction.

Consider a person pushing a cart with horizontal force $F$ through horizontal displacement $d$. Because the force and displacement point in the same direction, all of the force contributes to the work done.

For example, if $F = 20\,\text{N}$ and $d = 5\,\text{m}$:

$$W = (20\,\text{N}) \cdot (5\,\text{m}) = 100\,\text{N}\cdot\text{m}$$

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