Quick answer
This calculator finds the work done by a force and the power developed. Enter the force, the distance and the angle between them to get work in joules. Add the time to get power in watts, or use force and speed to find power directly.
Work done and power calculator
How to Use the Work and Power Calculator
- Choose “Work done” or “Power from force and speed”.
- For work, enter the force, the distance and the angle between the force and the direction of motion (0° if they point the same way).
- Optionally enter the time taken to get the power as well.
- Press Calculate.
Work and Power Formulas
| Quantity | Formula | Unit |
|---|---|---|
| Work done | W = Fd cos θ | joule (J) |
| Power | P = W ÷ t | watt (W) |
| Power at steady speed | P = Fv | watt (W) |
A force at right angles to the motion does no work, because cos 90° = 0. That is why carrying a bag along a flat corridor does no work on the bag in the physics sense. More in our work, energy and power guide.
Worked Example
Worked example: pulling a sledge
Question: A child pulls a sledge 20 m with a force of 40 N along a rope at 30° to the ground, taking 10 s. Find the work done and the power.
- W = Fd cos θ = 40 × 20 × cos 30°.
- W = 800 × 0.866 ≈ 693 J.
- P = W ÷ t = 693 ÷ 10 ≈ 69.3 W.
Answer: About 693 J of work is done at a power of about 69 W.
Learn more: see how to calculate work done in physics with solved examples.
Use this work and power calculator to check problems involving pushing, pulling and lifting, including forces applied at an angle.
Frequently Asked Questions
What is the difference between work and power?
Work is the energy transferred by a force, in joules. Power is how fast that work is done, in watts (joules per second).
When is no work done?
No work is done when the object does not move, or when the force is at right angles to the motion.
How many watts is one horsepower?
One mechanical horsepower is about 746 W.