Physics · Energy
Kinetic energy and work calculator.
Fill in whichever groups you need: mass and speed for kinetic energy, mass and height for potential energy, force, distance and angle for work, plus time for power.
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Energy, work and power formulas
Kinetic energy is K = ½mv², work is W = Fd cos θ, and average power is the work divided by the time, P = W ÷ t. The joule is one newton-metre; the watt is one joule per second. By the work-energy theorem the net work on an object equals its change in kinetic energy (OpenStax). Gravitational potential energy near a surface is mgh.
Worked example. A 2 kg object moving at 3 m/s has K = 9 J. Raised 10 m on Earth it holds mgh = 196.1 J. A 20 N force pushing it 5 m along its motion does W = 100 J (the same 100 J as HyperPhysics's example); if that takes 2 s the power is 50 W. If that work is the net work, the object's speed rises to 10.44 m/s.
Angle matters. Only the part of the force along the motion does work: 20 N over 5 m at 60° gives 50 J, and at 90° it gives zero.
The model treats the object as a point mass with constant force and no friction unless you include it in the net force. It is a classroom tool, not an engineering or lifting-safety calculation.
Frequently asked questions
What is the kinetic energy formula?
K = ½ × m × v². For 2 kg at 3 m/s that is 9 J.
How do I calculate work done by a force at an angle?
W = F × d × cos θ. For 20 N over 5 m at 60° the work is 50 J.
How is power related to work?
Average power is work divided by time. 100 J done in 2 s is 50 W.
What is the work-energy theorem?
The net work done on an object equals the change in its kinetic energy. Positive net work speeds it up, negative net work slows it down.
Which units does this use?
Kilograms, metres, seconds, newtons and degrees. Results are in joules and watts.
Sources
Checked
- OpenStax University Physics Volume 1, 7.1 Work
- OpenStax University Physics Volume 1, 7.2 Kinetic Energy
- OpenStax University Physics Volume 1, 7.3 The Work-Energy Theorem
- OpenStax University Physics Volume 1, 7.4 Power
- HyperPhysics: Work, Energy and Power
- NIST CODATA: standard acceleration of gravity (9.806 65 m/s2, exact)
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Scope
Idealised textbook formulas. Not for engineering, lifting or safety design. Results are arithmetic from the formulas shown, for study and general interest, and not professional or engineering advice.