The diagram shows a wind turbine.
(a) The blades of the turbine are 20 metres long. On average, 15 000 kg of air, moving at a speed of 12 m/s, hit the blades every second.
Using an appropriate equation, calculate the kinetic energy of the air hitting the blades
Show clearly how you work out your answer.
Kinetic energy = ......................... J
(b) Part of the kinetic energy of the wind is transformed into electrical energy.
The diagram shows that, for the same wind speed, the power output of a turbine, in kilowatts, depends on the length of the turbine blades.
Give a reason why doubling the diameter of the blades more than doubles the power output of a turbine.
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From Q4 P2 AQA January 2011 (Higher)