Conservation of Energy

The Undergraduate (2/3)

(part 1) A footloose undergraduate weighing 70 kg wants to bobsled down the Louvre. He pays the French government several million dollars in collateral, then sits on a bobsled on the top on of the Louvre. Then, he pushes himself off with a speed of 5 m/s. Assume the undergrad is 21 m above the ground and that $g$ = 9.8 m/s.

(continues from part 1) Luckily for our undergraduate, he is not going at more than 40 mph, because there is this thing called "friction". Assuming our daredevil rider loses 7070 J of energy whilst riding, what is his actual speed at the bottom? Round to the nearest tenth. Express you answer in m/s.