A girl and her bicycle have a total mass of 43.0 kg.At the top of the hill her speed is 5.0 m/s,and her speed doubles as she rides down the hill.The hill is 15.0 m high and 100 m long.How much kinetic energy and potential energy is lost to friction?

Question

Quizplus · Accepted Answer

The initial kinetic energy (KE_initial) is (1/2) * 43 * (5)^2 = 537.5 J. The final kinetic energy (KE_final) is (1/2) * 43 * (10)^2 = 2150 J. The potential energy at the top (PE_initial) is 43 * 9.8 * 15 = 6,321 J. The total mechanical energy at the top is KE_initial + PE_initial = 6,858.5 J. The total mechanical energy at the bottom is KE_final = 2150 J. The energy lost to friction is 6,858.5 J - 2150 J = 4,708.5 J, which rounds to 4,709 J.

A Girl and Her Bicycle Have a Total Mass of 43.0