Okuzeka
Physics vocabulary · Energy, Work and Momentum

Kinetic energy

Meaning in physics, with examples

/kɪˈnetɪk ˈenərdʒi/nounCore term

In physics, kinetic energy means: The energy an object has because it is moving. It depends on mass and speed and equals one half times mass times speed squared (½mv²).

In Turkish: kinetik enerji, hareket enerjisi

How it is used

Often shortened to KE or Eₖ. Because speed is squared, doubling the speed makes the kinetic energy four times larger, a point often used in road-safety discussions. Kinetic energy is gained, lost or converted.

Example sentences

  1. A car travelling at 20 m/s has four times the kinetic energy it has at 10 m/s.

  2. Some kinetic energy is lost as heat and sound when the ball hits the floor.

Common collocations

  • gain kinetic energy
  • lose kinetic energy
  • rotational kinetic energy
  • work-energy theorem
  • potential energyEnergy stored in an object because of its position or condition, for example a raised book or a stretched spring. Near the Earth's surface, gravitational potential energy equals mgh.
  • energyThe ability of a system to do work or cause change. It comes in many forms, such as kinetic, potential, thermal and chemical, and it is measured in joules (J).
  • conservation of energyThe principle that energy cannot be created or destroyed, only transferred between objects or converted from one form to another. The total energy of an isolated system stays constant.
  • workThe energy transferred when a force moves an object through a distance in the direction of the force. It equals force times displacement and is measured in joules (J).
  • elastic collisionA collision in which the total kinetic energy of the objects is the same before and after the impact. Momentum is conserved in every collision, but kinetic energy only in elastic ones.

More terms: Energy, Work and Momentum

Practise with graded reading

Reading at the right level is the fastest way to make new words stick. Pick free English books by level: