An electric winch with an efficiency of 70% is used to lift a crate of mass 80 kg vertically upwards at a constant speed of 1.25 m s-1.
Calculate the electrical input power of the winch.
(Take g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2.)
0.69 kW0.69\text{ kW}0.69 kW
0.98 kW0.98\text{ kW}0.98 kW
1.4 kW1.4\text{ kW}1.4 kW
2.0 kW2.0\text{ kW}2.0 kW
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.