Work & Power Calculator
Find work from force and distance, then power from work and time.
Work = force × distance when the force acts along the motion.
Power is the rate of doing work, in watts (J/s).
Work is force times the distance moved along that force: W = F × d, measured in joules. A 10 N force pushing an object 5 m does W = 10 × 5 = 50 J of work. Power is how fast that work is done, P = W ÷ t — doing those 50 J in 2 s is P = 50 ÷ 2 = 25 W.
What work and power mean
Work measures the energy transferred when a force moves an object through a distance: W = F × d. Power measures the rate at which that work is done, P = W ÷ t. Two motors can do the same 50 J of work, but the one that finishes in half the time delivers twice the power. The work you compute here is exactly the energy delivered, so it connects straight to kinetic energy and potential energy.
F = force (N), d = distance (m), W = work (J), t = time (s), P = power (W), θ = angle between force and motion
Worked example
You push a crate with a steady 10 N force and it slides 5 m in 2 s. How much work do you do, and at what power?
- 1 Find the work. W = F × d = 10 N × 5 m = 50 J. The force acts along the motion, so no angle correction is needed.
- 2 Note the time taken. The crate moves the 5 m in t = 2 s.
- 3 Divide work by time for power. P = W ÷ t = 50 J ÷ 2 s = 25 W — that is the average power delivered.
Work and power units
Work and energy share the joule; power is energy per second.
| Quantity | Symbol | SI unit | Definition |
|---|---|---|---|
| Work / energy | W | joule (J) | 1 J = 1 N × 1 m |
| Power | P | watt (W) | 1 W = 1 J/s |
| Horsepower | P | hp | 1 hp ≈ 746 W |
| Kilowatt | P | kW | 1 kW = 1000 W |
When no work is done, and the angle factor
Work needs motion along the force. If nothing moves, the distance is zero and W = 0 — holding a heavy box still is tiring but does no physical work. Likewise, carrying that box horizontally does no work against gravity, because gravity points down while the motion is sideways.
Angled forces use cos θ. When the force and the motion are not aligned, only the component along the path counts: W = F × d × cos(θ). At θ = 0° the force is fully effective (cos 0° = 1); at θ = 90° it does no work (cos 90° = 0).
Power is the rate of work. P = W ÷ t tells you how quickly energy is transferred. One watt is one joule per second, and 1 horsepower is about 746 watts.