According to Einstein's Special Theory of Relativity, as the velocity of an object increases relative to an observer in an inertial frame, its length becomes contracted according to

• $l_0={\gamma}l'$
where $l_0$ is the rest length of the object relative to an observer in the inertial frame, $l'$ is the contracted length of the moving object according to the same observer and ${\gamma}$ is the Lorentz Factor.