A boy in a wheelchair (total mass \( 47.0 \) \( \text{kg} \)) has speed \( 1.40 \) \( \text{m/s} \) at the crest of a slope \( 2.60 \) \( \text{m} \) high and \( 12.4 \) \( \text{m} \) long. At the bottom of the slope his speed is \( 6.20 \) \( \text{m/s} \). Assume air resistance and rolling resistance can be modeled as a constant friction force of \( 41.0 \) \( \text{N} \). Find the work he did in pushing forward on his wheels during the downhill ride.