# Talk:Theory of relativity/Special relativity

According to the classical theory, the kinetic energy of a body can be written as: ${\displaystyle {\frac {1}{2}}mv^{2}}$, where ${\displaystyle m}$ is the mass, and ${\displaystyle v}$ is the velocity of the body. According to the special theory of relativity, the kinetic energy of a body can be written as ${\displaystyle (\gamma -1)mc^{2}}$, where ${\displaystyle \gamma ={\frac {1}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}}$ is called the Lorentz factor. Prove that the classical theory would be correct, according to the special theory of relativity, if the speed of light would be infinite. In other words, prove that: ${\displaystyle \lim _{c\to \infty }(\gamma -1)mc^{2}={\frac {1}{2}}mv^{2}}$