A rescue sled carrying equipment is pulled up a rough, snow-covered mountain slope from a base camp to a higher rescue point by a motorized winch. Explain why the work done by the winch's cable on the sled is greater than the increase in the gravitational potential energy of the sled and its cargo.
57 exam-style questions on Edexcel GCSE Physics 8.1 Energy transfers and work. Each one has a worked solution and a mark scheme showing where the marks go.