How much energy will be necessary for making a body of 500 kg escape from the earth $[ \mathrm{g}=9.8\mathrm{m}/{\mathrm{s}}^2$ , radius of earth $=6.4\times {10}^6\mathrm{m} ]$

Potential energy of a body at the surface of earth

$\begin{array}{l}\mathrm{PE}=-\frac{\mathrm{GMm}}{\mathrm{R}}=-\frac{{\mathrm{gR}}^2\mathrm{m}}{\mathrm{R}}=-\mathrm{mgR}\\ =-500\times 9.8\times 6.4\times {10}^6=-3.1\times {10}^{10}\mathrm{J}\end{array}$

So if we give this amount of energy in the form of kinetic energy then body escape from the earth.