Kinetic energy is the energy of motion. A car at 100 km/h has four times the kinetic energy it has at 50 km/h, which is why braking distances and crash damage grow so quickly with speed.
How to use the Kinetic Energy Calculator
- Mass m
- Velocity v
- Every result field is editable: type into Kinetic energy and Velocity v plus every other field update to match.
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the mass and speed. Type an energy into the result to find the speed that gives it.
Inputs explained
| Field | What to enter |
|---|---|
| Mass m | Units: kg, g, mg, t, lb, oz |
| Velocity v | Units: km/h, m/s, mph, knots, ft/s |
What each result means
- Kinetic energy = [Mass m]×[Velocity v]^2÷2
- Momentum = [Mass m]×[Velocity v]
- Equivalent drop height = [Velocity v]^2÷(2×9.80665)
Example values
How the main result changes when Velocity v changes and everything else stays at the example values above:
| Velocity v (km/h) | Kinetic energy (J) |
|---|---|
| 50 | 144,675.9259 |
| 75 | 325,520.8333 |
| 100 | 578,703.7037 |
| 125 | 904,224.537 |
| 150 | 1,302,083.3333 |
| 200 | 2,314,814.8148 |
Formula
KE = ½·m·v²
Worked example
Inputs: Mass m: 1,500 kg; Velocity v: 100 km/h.
Results: Kinetic energy = 578,703.7037 J; Momentum = 41,666.6667 kg·m/s; Equivalent drop height = 39.3409 m.
Key terms
- Kinetic energy
- Energy of motion, ½mv².
Frequently asked questions
How does speed affect kinetic energy?
Doubling the speed quadruples the energy.
What is the kinetic energy of a 1,500 kg car at 100 km/h?
About 579 kJ.
Can kinetic energy be negative?
No, mass and v² are never negative.
What happens to kinetic energy in a crash?
It becomes heat, sound and deformation.