Calculator for Movement or Kinetic Energy

Please enter two values, the third value will be calculated. The formula for the movement energy or kinetic energy is E = m v² / 2, the unit joule is calculated as kilograms times square meters per square second, 1 J = 1 kg * m² / s².

Example: a 1500 kilograms heavy car is brought to a speed of 80 km/h. The energy needed to do this without friction is about 370 kilojoules.

Kinetic energy is the energy that a body receives through movement. The expression comes from the ancient Greek word kinesis, which means motion. It corresponds to the energy that must be expended to bring a body from a state of rest to this speed or to make a corresponding change in the level of speed. This only applies to speeds far below the speed of light, where relativistic effects do not play a role. But these are actually all the speeds that we normally have to deal with. Kinetic energy can be stored as potential energy, for example in a body that is resting at a height and gains motion, thus releases kinetic energy when it falls.

The factor 1/2 in the formula is calculated as follows: Force is mass times acceleration, F=m*a. Velocity is acceleration times time, v=a*t. Distance is velocity times time, s=v*t, or half the acceleration times time squared, s=a*1/2*t². Acceleration is the derivative of velocity with respect to time. If you differentiate t², you get 2t, so to get t, you must differentiate 1/2*t². Energy is force times distance, E=F*s =m*a*a*1/2*t² =1/2*m*v²