Physics 11 · Physics · Lesson 5.1
Work & Power
- Level
- Grade 11
- Reading time
- 12 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Transferring energy over distance.
What are work and power in physics?
Short answer
Work is energy transferred when a force moves an object through a distance in the force’s direction: W = Fd, measured in joules. Power is the rate at which work is done or energy is transferred: P = W/t, measured in watts. Doing the same work in less time requires more power.
Concept preview
What you will be able to do
- 01Define work and calculate it with W = Fd cosθ
- 02Distinguish positive, negative and zero work
- 03Calculate power as the rate of doing work (P = W/t = Fv)
In everyday speech 'work' means effort. In physics it means something sharper: work is done when a force moves something through a distance. Push a box 3 m across the floor and you've done work on it; strain against a wall that doesn't budge and — however exhausted you feel — you've done zero physical work, because nothing moved. The simplest case, force and motion in the same direction, is , measured in joules (J), where .
School Plan
Work & Power
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Related topics
Frequently asked questions
- When is no work done despite a force?
- When the force is perpendicular to the motion, or the object does not move, the work done by that force is zero.
- What is the difference between work and power?
- Work is the total energy transferred; power is how fast that energy is transferred.