Total energy

E=\gamma mc^2

Result unit: J (joule)

What it describes

The total energy of a body in motion — it includes the rest energy and the kinetic energy.

E

total energy

[J]

\gamma

Lorentz factor

m

rest mass

[kg]

c

speed of light

[m/s]

The total energy of a body grows with speed. At rest (

\gamma=1

) it gives the rest energy

mc^2

; the difference

E-mc^2

is the relativistic kinetic energy.

Particles at speeds close to

c

(accelerators). As

v\to c

the energy tends to infinity.

A particle of mass 1 kg has

\gamma=2

. Calculate the total energy.

Substitution

\gamma=2

c=3\cdot10^{8}

Result

E=2\cdot1\cdot(3\cdot10^{8})^2=1.8\cdot10^{17}

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