As well as lifting an object, a force can make it accelerate. Again, work is done by the force and energy is transferred to the object. In this case, we say that it has gained kinetic energy, ${E_k}$. The faster an object is moving, the greater its kinetic energy (k.e.).
For an object of mass m travelling at a speed v, we have:

$\begin{array}{l}
kinetic\,energy\, = \,\frac{1}{2}\, \times \,mass\, \times \,spee{d^2}\\
{E_k} = \,\frac{1}{2}m{v^2}
\end{array}$

Deriving the formula for kinetic energy

The equation for kinetic energy, ${E_k} = \frac{1}{2}m{v^2}$ , is related to one of the equations of motion. We imagine a car being accelerated from rest ($u = 0$) to velocity v. To give it acceleration a, it is pushed by a force F for a distance s. Since u = 0, we can write the equation ${v^2} = {u^2} + 2as$ as:

${v^2} = 2as$

Multiplying both sides by $\frac{1}{2}m$ gives:

$\frac{1}{2}m{v^2} = mas$

Now, ma is the force F accelerating the car, and mas is the force $ \times $ the distance it moves (that is, the work done by the force). So we have:

$\frac{1}{2}m{v^2} = work\,done\,by\,force\,F$

This is the energy transferred to the car, and hence its kinetic energy.