A spherical body of mass 100" " g is dropped from a height of 10" " m from the ground. After hitting the ground, the body rebounds to a height of 5" " m. The impulse of force imparted by the ground to the body is given by : $\left(\right.$ given $\left.\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^2\right)$