Kinetic Energy Calculator
How much energy does a moving object carry?
Your numbers
Your results
Kinetic energy (J)
Kinetic energy (J)
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Kinetic energy (kJ)
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Kinetic energy (kWh)
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Speed (km/h)
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Momentum (kg·m/s)
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Kinetic Energy Calculator by TheCalcTools
How the Kinetic Energy Calculator works
Enter the mass and speed in SI units.
Kinetic energy is half the mass times the speed squared.
Doubling the speed quadruples the energy.
The formula
KE = ½ m v²p = m v
Worked example
Using the default values shown in the calculator:
| Mass (kg) | 1000 |
|---|---|
| Speed (m/s) | 20 |
- KE = ½ × 1,000 × 20² = 200,000 J.
- That is 200 kJ, at a speed of 72 km/h.
Result:
| Kinetic energy (J) | 200,000 |
|---|---|
| Kinetic energy (kJ) | 200.00 |
| Kinetic energy (kWh) | 0.0556 |
| Speed (km/h) | 72.0 |
| Momentum (kg·m/s) | 20,000 |
Frequently asked questions
Why does speed matter so much?
Energy grows with the square of speed. A car at 100 km/h has four times the energy of one at 50 km/h, which is why stopping distances grow so quickly.
Is kinetic energy conserved in a crash?
Not in an inelastic collision. Some is converted to heat, sound and deformation.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.