Relativistic kinetic energy is energy possessed by any object due to motion when the effect of relativity is accounted for.  For most objects traveling at small fractions of the speed of light, relativistic effects are generally insignificant for practical application.  However, when the speed of a mass is a significant fraction of the speed of light, then it is necessary to account for relativistic effects to produce usable calculations of kinetic energy.

This equation computes the relativistic kinetic energy E_K for a mass traveling at a relativistic velocity.  If the speed of the mass, m, is a significant portion of the speed of light, c, it is necessary to use the this equation to compute the Kinetic Energy.

Definition

The equation for Kinetic Energy, E_K bears resemblance to the famous Mass-Energy Equivalence equation, E = mc² introduced by Einstein, which includes both kinetic energy and rest mass energy.  The equation for kinetic energy alone is the deduction of the rest mass energy component from this total.

The kinetic energy is equivalent to the work required to accelerate an object from rest to the speed, v.   Therefore, as can be seen from the equation, as v approaches the the speed of light, the resulting energy approaches infinity.  Thus, an infinite amount of work (an apparent impossibility) is required to accelerate a mass to the speed of light.

See also

• Kinetic Energy