The energy of a body is the ability (or capacity) of the body to do work.

Half of the product of the mass of a body and the square of its velocity is defined as kinetic energy $(K)$ of the body.

$\therefore \quad \mathrm{K}=\frac{1}{2} m v^{2}$ where $m=$ mass of body

$\nu=$ velocity or speed of the body.

Unit of kinetic energy is same as the unit of work. So, its $SI$ unit is Joule $(J)$ and $CGS$ unit is erg. Dimensional formula of kinetic energy is $\left[\mathrm{M}^{1} \mathrm{~L}^{2} \mathrm{~T}^{-2}\right]$.

Hence, a body of definite mass moving with more speed would have more kinetic energy compared to the kinetic energy of the same body moving with comparatively lesser speed.

Kinetic energy is a scalar quantity. The kinetic energy of a body indicate the magnitude of work by the body during its motion.

The kinetic energy of a fast flowing stream has been used to grind grains.

Sailing ships employ the kinetic energy of the wind and electricity is generated by wind mill.