An electric winch of efficiency 0.70 is used to raise a load of mass 400 kg vertically through a height of 15 m at a constant speed.
Taking g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2, calculate the energy wasted by the winch during this operation.
17.64 kJ17.64\text{ kJ}17.64 kJ
25.20 kJ25.20\text{ kJ}25.20 kJ
58.80 kJ58.80\text{ kJ}58.80 kJ
84.00 kJ84.00\text{ kJ}84.00 kJ
37 exam-style questions on OCR GCSE Physics Power and efficiency. Each one has a worked solution and a mark scheme showing where the marks go.