Describe — 2 marks
A student is conducting an experiment to measure the density of different materials. They measure the mass of a copper block as 178.5 g and its volume as 20 cm³. To find the density, they need to divide the mass by the volume.
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Describe the steps you would follow to calculate the density of the copper block using the values 178.5 g and 20 cm³.
[2 marks]
Show mark scheme
- {'mark': 1, 'description': 'Divide 178.5 by 20 (or equivalent statement showing correct operation)'}
- {'mark': 1, 'description': 'Obtain the answer of 8.925 g/cm³ (or 8.9 g/cm³ to 1 d.p.) with correct units'}
Explain — 3 marks
A student is investigating the efficiency of different renewable energy systems. A solar panel array produces 2.5 kW of power on a sunny day. However, due to system losses, only 3/4 of this power is actually delivered to the home. On a cloudy day, the output is reduced by 0.4 of the sunny day's delivered power.
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(a) Calculate the power actually delivered to the home on a sunny day. Show your working.
[1 mark]
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(b) Calculate the power delivered on a cloudy day. Show your working.
[1 mark]
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(c) Explain why the difference between sunny and cloudy day outputs (as a fraction of the sunny day delivered power) is important when designing a battery storage system for the home.
[1 mark]
Show mark scheme
- (a) Award 1 mark for correctly calculating 2.5 × 3/4 = 1.875 kW (or 1.88 kW to 2 d.p.)
- (b) Award 1 mark for correctly calculating 1.875 - (0.4 × 1.875) = 1.125 kW (or 1.13 kW to 2 d.p.)
- (c) Award 1 mark for explaining that the significant variation/difference in power output between weather conditions means the battery must be sized large enough to store sufficient energy to meet demand during low-output periods (cloudy days)
GCSE Perfect