How to calculate kinetic energy
Kinetic energy is the energy an object has because it is moving. It depends on mass and, much more strongly, on speed: because velocity is squared in the formula, doubling the speed gives four times the energy.
The kinetic energy formula
KE = 1/2 x m x v squared, where m is mass in kilograms and v is velocity in metres per second. The result is in joules.
Worked example
A 2 kg object moving at 3 m/s has a kinetic energy of 0.5 x 2 x 3 x 3 = 9 joules.
Frequently asked questions
What is kinetic energy?
The energy of motion. Any moving object has kinetic energy equal to half its mass times its velocity squared.
Why does speed matter so much?
Because velocity is squared in the formula. Doubling speed quadruples the kinetic energy, which is why crashes at higher speeds are far more severe.
What unit is kinetic energy in?
Joules, when mass is in kilograms and velocity is in metres per second.