Question

A child riding a bicycle has a total mass of 40kg. The child approaches the top of a hill that is 10m high and 100m long at 5m/s. If the force of friction between the bicycle and the hill is 20N, what is the child's velocity at the bottom of the hill? (Assume no air resistance and that g=9.81m/s)

Answer 1

Energy used up by friction:20N(100m)
energy gained by bike: 40*9.8*10

Ke at bottom=energy gained minus friction

veloctiy at bottom=sqrt(2KE/mass)