Kinetic Energy Calculator
Find kinetic energy from mass and velocity.
Result
Kinetic energy (J)
9.00
How it works
Kinetic energy is the energy of motion: Ek = ½·m·v², in joules. A 1,000 kg car at 20 m/s carries 200,000 J — the energy that has to go somewhere when it stops. The square on the velocity is the whole story. Double the speed and the energy quadruples; triple it and you have nine times as much. That is why stopping distances grow so fast with speed, why a crash at 100 km/h is far more than twice as violent as one at 50, and why speed limits are set on energy rather than on speed alone. When a moving object stops, that energy is not destroyed but converted — into heat in the brakes, into deformation of crumpled metal, into sound. Crumple zones exist precisely to absorb kinetic energy over a longer distance so that less of it reaches the occupants.
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Frequently asked questions
What is the kinetic energy formula?
KE = ½ · m · v².
Does doubling speed double the energy?
No — energy depends on v², so doubling speed gives four times the energy.
What is the difference from momentum?
Momentum is m·v and kinetic energy is ½·m·v². Double the speed and momentum doubles but energy quadruples — momentum governs collisions, energy governs damage and stopping distance.
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