An electric hoist is used to raise a crate of mass 250 kg vertically at a constant speed of 1.2 m s-1. The hoist has an efficiency of 75%. Taking g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2, find the total input power of the hoist.
2.21 kW2.21\text{ kW}2.21 kW
2.94 kW2.94\text{ kW}2.94 kW
3.92 kW3.92\text{ kW}3.92 kW
0.40 kW0.40\text{ kW}0.40 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.