alleryStart learning →Work done by a constant force $\vec{F}$ when the body moves through displacement $\vec{s}$ is:
- $W = F + s$
- $W = F s \cos\theta$
- $W = F s \sin\theta$
- $W = F / s$
Show answer and solution
Correct answer: B. $W = F s \cos\theta$
Work is defined as $W = \vec{F} \cdot \vec{s} = F s \cos\theta$, where $\theta$ is the angle between $\vec{F}$ and $\vec{s}$.
Work is maximum ($Fs$) when force and displacement are parallel and zero when they are perpendicular ($\cos 90° = 0$). Negative work happens when force opposes motion (e.g. friction).