O-LevelPhysicsEnergy & Work5054/21 · May/June 2022 · Q28 Marks

Fig. 2.1 shows a wind turbine.[Figure 2.1]

(a)The wind blows directly towards the turbine with a speed of 12m/s. In one second, 60000 kg of air passes through the circular area swept out by the blades. Calculate the kinetic energy of this mass of air.[3]
(b)(i)A wind turbine releases no carbon dioxide into the atmosphere while generating electricity. Compared with a coal-fired power station, this is an advantage of using a wind turbine. State one reason why it is important to reduce the amount of carbon dioxide produced.[1]
(b)(ii)Suggest one advantage of using a coal-fired power station compared with a wind turbine.[1]
(c)(i)A coal-fired power station releases 0.96 kg of carbon dioxide when it generates 1.0kWh of electrical energy. Define the kilowatt-hour (kWh).[1]
(c)(ii)Calculate the mass of carbon dioxide saved when the wind turbine has a power output of 2000 kW and operates for 12 hours.[1]
(d)Wind energy is a form of renewable energy. State the name of one other form of renewable energy.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[1] (a) (K.E. =) ½mv² numerical or algebraic
[1] (a) 0.5 × 60 000 × 12²
[1] (a) 4 300 000 J
[1] (b)(i) reduces global warming
[1] (b)(ii) wind not always blowing or wind not reliable / not available in some places or smaller land area (for same power) or less harm to birds or less visual effect or no interference with tv / radar signals
[1] (c)(i) (amount of energy of a device of power) 1 kW used for 1 hour
[1] (c)(ii) 23 000 kg
[1] (d) solar, tidal, geothermal, hydro(electric), biomass, wave

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