Kinetic Energy Calculator (KE = ½·m·v²)
Compute the kinetic energy of a moving object from its mass and speed. Result in joules with kcal and ft·lb conversions.
Result
Kinetic energy
578,796.30 J
- In kilojoules578.796 kJ
- In nutritional kcal138.3356 kcal
- In foot-pounds426,898.24 ft·lb
Step-by-step
- KE = ½ × m × v².
- v² = 27.78² = 771.7284 m²/s².
- KE = 0.5 × 1,500 kg × 771.7284 m²/s² = 578,796.30 J.
How to use this calculator
- Enter the mass in kilograms.
- Enter the speed in metres per second. Convert from mph if needed: v(m/s) = mph × 0.447.
- Read kinetic energy in joules and useful unit conversions.
About this calculator
Kinetic energy is the energy an object carries because it is moving. It scales linearly with mass but with the square of speed — doubling the speed quadruples the KE. That is why crash severity rises so sharply with speed: a car at 60 mph carries four times the kinetic energy of the same car at 30 mph. The formula KE = ½·m·v² comes from integrating force over distance using Newton's second law. Kinetic energy is converted to heat, sound, and deformation in collisions, and to potential energy when an object is lifted.
Frequently asked
Because work (force × distance) is needed to accelerate. Stopping distance grows linearly with speed, but the force × distance integral grows quadratically. That is also why braking distance roughly quadruples when you double speed.
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