A boy in a wheelchair (total mass, 46.9kg) wins a race with a skateboarder. He has a speed of 1.30m/s at the crest of a slope 2.35m high and 12.6m long. At the bottom of the slope, his speed is 6.28m/s. If air resistance and rolling resistance can be modeled as a constant frictional force of 41.3N, calculate the work he did in pushing forward on his wheels during the downhill ride.

1 answer

work done:
gain in energy=mgh+initial KE-final KE
friction energy=41.3*12.5

work he did: friction energy-gain in energy