A car of mass 1200 kg travels up a hill inclined at an angle θ \theta\,θ to the horizontal, where sinθ=114\displaystyle \sin\theta = \frac{1}{14}sinθ=141. The resistance to motion is a constant 400 N. The car's engine has an efficiency of 75% and the car travels up the hill at a constant speed of 15 m s-1.
Using g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2, calculate the input power of the car's engine.
13.95 kW13.95\text{ kW}13.95 kW
18.6 kW18.6\text{ kW}18.6 kW
24.8 kW24.8\text{ kW}24.8 kW
8.0 kW8.0\text{ kW}8.0 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.