A body of mass $1 \mathrm{kg}$ is connected to a string and is undergoing a complete vertical circular motion of radius $1 \mathrm{m}$. If it is barely able to complete the vertical circle, then the difference in its kinetic energy at the top and bottom of the circle is (Take $g=10\mathrm{ }\mathrm{m}{\mathrm{s}}^{-2}$)