# Kinetic energy

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A basic diagram showing potential energy (Rankine, 1853), or "energy of configuration", transformed into kinetic energy (Thomson, 1862), or "energy of motion". Also shown are the 1769 terms "force morte" and "force vive", as used by Denis Diderot, in his Alembert's Dream (§1.8), one of several forerunner terms.

In terms, kinetic energy (TR:140) (LH:15) (TL:155) refers the energy associated with a body in motion, defined by ½ the product of its mass and velocity squared.

## Overview

In 1862, William Thomson and Peter Tait, in their “Energy”, building of Thomas Young's 1807 term "energy", referring to a body with velocity, and William Rankine's 1853 term "actual energy", introduced the term “kinetic energy”, as follows:

“We are led to measure the ‘kinetic energy’ by the square of the velocity with which a body moves.”
— William Thomson (1862), “Energy” (co-author: Peter Tait) (pg. 602) [1]

In c.1864, kinetic energy, with the additive ½ factor, came to be defined as:

${\displaystyle E_{k}={\frac {1}{2}}mv^{2}}$

In 1865, kinetic energy and potential energy became subsumed into Rudolf Clausius' "internal energy" formulation of the first law of thermodynamics.

## Quotes

The following are quotes:

“The name kinetic energy, which I subsequently gave as seeming preferable to ‘actual energy’, has been generally adopted; but Rankine’s name ‘potential energy’ remains to this day, and is universally used to designate energy of the static kind.”
William Thomson (1882), “On the Mechanical Values of Distributions of Electricity, Magnetism, and Galvanism” [2]