You and your little brother are sled$-$riding at your favorite spot. The hill is covered in snow and the friction between the sled and snow is negligible. You pull your $27-$kg little brother sitting in an $8-$kg sled to the top of the hill $($see the figure below$).$

Once at the top, you give him a push so that he has an initial speed of $2\mathrm{.}2$ m$/$s$.$ He heads down the hill through a little dip and up the other side onto level ground.

Calculate his final speed after again reaching level ground.