A man in a balloon throws a stone downwards with a speed of 5 m/s with respect to balloon. The balloon is moving upwards with a constant acceleration of 5 $\mathrm{m}/{\mathrm{s}}^2. \mathrm{Then} \mathrm{velocity} \mathrm{of} \mathrm{the} \mathrm{stone} \mathrm{relative} \mathrm{to} \mathrm{the} \mathrm{man} \mathrm{after} 2 \mathrm{seconds} \mathrm{is}$