What Is Work in Physics? Calculate Work on a Lawn Mower

Answer

In physics, a constant force does work according to the dot product of force and displacement:

$$W=Fd\cos\theta,$$

where $\theta$ is the angle between the force and the displacement.

Here the displacement is horizontal, so

$$W=(75.0\,\text{N})(25.0\,\text{m})\cos(35.0^\circ).$$ $$W\approx 1.54\times10^3\,\text{J}.$$

So the person does about $1.54\,\text{kJ}$ of work on the mower.

Only the component of the force parallel to the displacement contributes. The downward component of the push is perpendicular to the mower’s horizontal displacement and therefore contributes zero work to this calculation.