A 40-kg sled rests at the top of a 34˚ incline that is 500 m long.
If the coefficient of friction is 0.2, what will be the speed at the
bottom of the slope? The 40-kg mass includes the mass of the
person on the sled.
K.E. gained during descent = P.E. loss - (work against friction)
(M/2)Vf^2 = M*g*500sin34 - M*g*cos34*500*0.2
Mass M cancels out
Vf^2 = 1000*g*sin34 - 200*g*cos34
= 5480 - 1625 = 3855
Vf = 62 m/s
That is 138 mph. Even bobsleds do not go that fast. The assumptions are unrealistic.