An explosive charge giving an impulse of $4$ kN s is used to discharge a $1\mathrm{.}3$ t satellite from a spaceship in steady flight. The mass of vehicle remaining after separation is $1\mathrm{.}1$ t$.$ What is the speed of recession of the two parts, assuming the final motions to be in the line of flight? Show that the energy of the explosion appearing as additional kinetic energy is about $13\mathrm{.}4$ kJ$.$