Work, Energy and Power Calculator

What is work in physics?

Work is done when a force moves an object. It is the component of the force along the motion multiplied by the distance moved: W = F × d × cos θ. The unit is the joule (J): one joule is the work done when a force of 1 newton moves an object 1 metre.

The angle matters. If the force acts along the motion (θ = 0), all of it counts. If the force is perpendicular to the motion (θ = 90°), the work is zero: carrying a bag along a level path, the upward force from your arm does no work in the physics sense.

What is power?

Power is how fast work is done: P = W / t. The unit is the watt (W), and 1 watt is 1 joule per second. For an object moving at constant speed, power is also P = F × v.

Energy

Energy is the capacity to do work and is measured in the same unit. Power multiplied by time gives the energy used: W = P × t. The kilowatt hour on an electricity bill is this product: 1 kWh = 3.6 million joules.

Example

Pushing a crate 5 metres with a force of 200 N does 200 × 5 = 1000 J of work. If that takes 4 seconds, the power is 1000 / 4 = 250 W.

Limits

The calculation is for a constant force. For forces that change along the path, such as a spring force, the formula cannot be used directly. Kinetic and potential energy have their own calculators.