web viewcarbon dioxide causes visual pollution. (1) ... the students were able to answer this...
TRANSCRIPT
GCSE Physics Revision: 1) Energy V1
Q1.(a) The pie chart shows the proportions of electricity generated in the UK from different
energy sources in 2010.
(i) Calculate the percentage of electricity generated using fossil fuels.
______________________________________________________________
Percentage = ______________________ %(1)
(ii) The pie chart shows that 7% of electricity was generated using renewable energy sources.
Which one of the following is not a renewable energy source?
Tick ( ) one box.
Oil
Solar
Wind
(1)
(b) Complete the following sentence.
In some types of power station, fossil fuels are burned to heat ________________ to produce steam.
(1)
(c) Burning fossil fuels releases carbon dioxide into the atmosphere.
GCSE Physics Revision: 1) Energy V1Why do many scientists think adding carbon dioxide to the atmosphere is harmful to the environment?
Tick ( ) one box.
Carbon dioxide is the main cause of acid rain.
Carbon dioxide causes global warming.
Carbon dioxide causes visual pollution.
(1)(Total 4 marks)
Q2.A student investigated the specific heat capacity of metals.
(a) Describe an experiment the student could do to measure the specific heat capacity of a metal.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(6)
(b) The student calculated the specific heat capacity of four metals.
The table below shows the student’s results.
GCSE Physics Revision: 1) Energy V1
Metal Mass of material in
kg
Time in minutes
Temperaturein °C
Change in thermal
energy in J
Calculated specific heat capacity of
materialin J / kg °C
Aluminium 1 10 2 4 780 2 390
Brass 1 10 4 4 660 1 165
Copper 1 10 4 600 657
Steel 1 10 5 4 690 938
Use data from the table above to calculate the temperature change for copper.
Use the correct equation from the Physics Equation Sheet.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Temperature change = ________________ °C(3)
(c) What is the independent variable in the student’s investigation?
Tick one box.
Mass of material
Power used
Time in minutes
Type of material
(1)
GCSE Physics Revision: 1) Energy V1
(d) The student calculated the specific heat capacity of aluminium to be 2390 J / kg °C.
The ‘true’ specific heat capacity of aluminium is 900 J / kg °C.
Suggest why the student’s result for aluminium is different from the ‘true’ value.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(e) The teacher suggested that putting bubble wrap round the metal block would change the results.
How would using bubble wrap change the results?
Give a reason for your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(Total 14 marks)
Q3.The figure below shows a rollercoaster.
The rollercoaster car is raised a vertical distance of 35 m to point A by a motor in 45 seconds.
The mass of the rollercoaster is 600 kg.
The motor has a power rating of 8 000 W.
GCSE Physics Revision: 1) Energy V1
(a) Calculate the percentage efficiency of the motor.
Gravitational field strength = 9.8 N / kg.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Efficiency = __________________ %(5)
(b) The rollercoaster rolls from point A to point B, a drop of 35 m.
Calculate the speed of the roller coaster at point B.
Assume that the decrease in potential energy store is equal to the increase in kinetic energy store.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Speed at point B = __________________ m / s(6)
(Total 11 marks)
GCSE Physics Revision: 1) Energy V1
Q4.The miners working in a salt mine use smooth wooden slides to move quickly from one level to another.
(a) A miner of mass 90 kg travels down the slide.
Calculate the change in gravitational potential energy of the miner when he moves 15 m vertically downwards.
gravitational field strength = 10 N/kg
Show clearly how you work out your answer.
___________________________________________________________________
___________________________________________________________________
Change in gravitational potential energy = _________________________ J(2)
(b) Calculate the maximum possible speed that the miner could reach at the bottom of the slide.
Show clearly how you work out your answer.
Give your answer to an appropriate number of significant figures.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Maximum possible speed = _________________________ m/s(3)
GCSE Physics Revision: 1) Energy V1
(c) The speed of the miner at the bottom of the slide is much less than the calculated maximum possible speed.
Explain why.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
(Total 8 marks)
Q5.Over the next 15 years, some of the older nuclear power stations will be closed down, and the process of decommissioning will start. In the same period, several countries plan to build a number of new nuclear power stations.
(a) (i) What does it mean to decommission a nuclear power station?
______________________________________________________________
______________________________________________________________(1)
(ii) How does decommissioning affect the overall cost of electricity generated using nuclear fuels?
______________________________________________________________
______________________________________________________________(1)
(b) Uranium is a fuel used in nuclear power stations to generate electricity.
Graph 1 compares how the electricity generated from one kilogram of nuclear fuel changed between 1980 and 2005 in three different types of nuclear power station.
GCSE Physics Revision: 1) Energy V1
(i) Compare the efficiency of the three types of power station, K, L and M, between 1980 and 2005.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
Graph 2 shows two different predictions for the global growth in uranium demand over the next few years.
(ii) Suggest reasons why it is not possible to predict accurately how much uranium will be needed in 2025.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(Total 6 marks)Q6.
(a) In the UK, over 70% of the electricity is generated in power stations that burn fossil
GCSE Physics Revision: 1) Energy V1fuels.
(i) Explain one effect that burning fossil fuels has on the environment.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________(2)
(ii) Give one way the effect on the environment described in part (a)(i) could be reduced.
Assume the amount of fossil fuels burnt stays the same.
______________________________________________________________
______________________________________________________________(1)
(b) Electricity can also be generated in a pumped storage hydroelectric power station.
An advantage of pumped storage hydroelectric power stations is the short start-up time they have.
(i) What is the importance of the short start-up time?
______________________________________________________________
______________________________________________________________(1)
(ii) Give one other advantage of a pumped storage hydroelectric power station.
______________________________________________________________
______________________________________________________________(1)
(c) Read the extract below from a newspaper article.
(i) In the UK, the proportion of electricity generated using wind turbines is due to increase a lot. Some opponents of wind turbines think this increase will cause big fluctuations in the electricity supply.
Suggest one reason why this may be true.
______________________________________________________________
______________________________________________________________
GCSE Physics Revision: 1) Energy V1(1)
(ii) Between 2002 and 2008 the amount of electricity used for lighting in homes in the UK decreased.
Suggest one reason why.
______________________________________________________________
______________________________________________________________(1)
(Total 7 marks)
Q7.(a) Iceland is a country that generates nearly all of its electricity from renewable
sources.
In 2013, about 80% of Iceland’s electricity was generated using hydroelectric power stations (HEP).
Describe how electricity is generated in a hydroelectric power station. Include the useful energy transfers taking place.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(4)
(b) The UK produces most of its electricity from fossil fuels.
Many people in the UK leave their televisions in ‘stand by’ mode when not in use, instead of switching them off.
It is better for the environment if people switch off their televisions, instead of leaving them in ‘stand by’ mode.
Explain why.
___________________________________________________________________
GCSE Physics Revision: 1) Energy V1___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(3)
GCSE Physics Revision: 1) Energy V1
(c) A scientist wrote in a newspaper:
‘Appliances that do not automatically switch off when they are not being used should be banned.’
Suggest why scientists alone cannot make the decision to ban these appliances.
___________________________________________________________________
___________________________________________________________________(1)
(Total 8 marks)
Q8.A student investigated the specific heat capacity of five different metal cylinders.
Each metal cylinder had a mass of 2 kg.
He used an immersion heater to transfer 18 000 J of energy to each different metal cylinder.
Figure 1 shows the apparatus he used.
Figure 1
He measured the temperature of the metal cylinder at the start and at the end of each experiment, using a thermometer.
He calculated the temperature rise of each metal cylinder.
The results are shown in Figure 2.
GCSE Physics Revision: 1) Energy V1 Metal cylinder
(a) Suggest an appropriate resolution for the thermometer used in the investigation.
Resolution = _______________________ °C
Give a reason for your answer.
___________________________________________________________________
___________________________________________________________________(2)
(b) The mass of metal and the energy transferred to each metal were control variables in the investigation.
Suggest another variable that should have been controlled.
___________________________________________________________________(1)
(c) Which metal has the highest specific heat capacity? ___________________
Give a reason for your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(d) In this investigation, 18 000 J of energy was supplied to a 2 kg cylinder of steel.
Calculate the specific heat capacity of steel.
Use the correct equation from the Physics Equations Sheet.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Specific heat capacity = _______________________ J / kg °C(3)
(Total 8 marks)
Q9.Electricity in the UK is generated in many ways.
The figure below shows an undersea turbine.
The undersea turbine uses tidal energy to generate electricity.
GCSE Physics Revision: 1) Energy V1
© alex-mit/iStock/Thinkstock
(a) What is the original source of energy for tidal power schemes?
___________________________________________________________________
___________________________________________________________________(1)
(b) Explain two advantages of using undersea tidal turbines to generate electricity rather than burning fossil fuels.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(4)
(c) Some power stations burn wood instead of fossil fuels to generate electricity.
A coal-burning power station burns 6 million tonnes of coal per year.
Coal has an average energy value of 29.25 MJ per kg.
Wood chip from willow trees has an energy value of 13 MJ per kg.
A hectare of agricultural land can produce 9 tonnes of dry willow wood per year.
If this power station burned dry willow wood instead of coal, how much agricultural land would be needed to grow the willow?
GCSE Physics Revision: 1) Energy V1___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Amount of land needed = _____________ hectares(3)
(d) The table below shows the carbon dioxide emissions of four fuels used to generate electricity.
Fuel Direct CO2 emissionsin kg per MWh
Lifecycle CO2
emissionsin kg per MWh
Coal 460 540
Natural gas 185 215
Oil 264 313
Wood 2 100 58
Direct CO2 emissions are the amounts of carbon dioxide released when the fuel is burned.
Lifecycle CO2 emissions is the total amount of carbon dioxide released during all stages from fuel extraction to when the fuel has been used.
Use the data from the table above to explain why wood is considered to be a low carbon dioxide emitting fuel.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________(2)
(Total 10 marks)
GCSE Physics Revision: 1) Energy V1
Mark schemes
Q1.(a) (i) 77
1
(ii) Oil1
(b) wateraccept H2O
1
(c) Carbon dioxide causes global warming1
[4]
Q2.(a) Level 3 (5–6 marks):
A full, detailed and coherent plan covering all the major steps is provided, which outlines what needs to be measured to calculate specific heat capacity. The steps are set outin a logical manner that could be followed by another person to calculate the specificheat capacity.
Level 2 (3–4 marks):The substantive content of a plan is present but may be missing some steps. The planmay not be in a completely logical sequence but leads towards the calculation of thespecific heat capacity.
Level 1 (1–2 marks):Simple statements relating to relevant apparatus or steps are made but they may not bein a logical order. The plan would not allow another person to calculate specific heat capacity.
0 marks:No relevant content.
Indicative content• measure the mass of metal• correct use of balance• description of how work is done or energy transferred to metal
eg electrical work, mechanical work (eg dropping lead shot)• how energy transfer or work done is measured
eg electrical using joulemeter, mechanical decrease in potential energy store of falling lead shot
• equate work done / energy transferred = increase in thermal energy store of themetal
• calculate specific heat capacity6
(b) 4 600 = 1 × 657 × temperature change1
GCSE Physics Revision: 1) Energy V1temperature change = 4 600 / 657
1
= 7 (°C)allow 7 with no working shown for 3 marks
1
(c) Type of material1
(d) heat loss1
then any one from:
• turned off the power supply too early• incorrectly measured mass of material• incorrectly measured temperature• incorrectly read the change in thermal energy
1
(e) would give a more accurate value or the calculated specific heat capacity will be smaller
1
because the bubble wrap insulates the material or prevents heat loss1
[14]
Q3.(a) 600 kg = 5880 N
1
power = 1
= 4573.3 (W)this step without the previous steps stated gains 3 marks
1
% Eff. = 1
= 57.17 (%)allow 57.17 with no working shown for 5 marks
1
(b) gpe = 600 × 9.8 × 351
= 205 8001
gpe = KE = ½ m v2
1
GCSE Physics Revision: 1) Energy V1
v = 1
1
= 26.2 (m / s)allow 26.2 with no working shown for 6 marks
1[11]
Q4.(a) 13 500 (J)
allow 1 mark for correct substitution, ie 90 x 10 x 15 provided no subsequent step shown
2
(b) 17or
correctly calculated and answer given to 2 or 3 significant figuresaccept 17.3allow 2 marks for an answer with 4 or more significant figures, ie 17.32orallow 2 marks for correct substitution, ie 13 500/ their (a) = ½ x 90 x v2
orallow 1 mark for a statement or figures showing KE = GPE
3
(c) work is done1
(against) friction (between the miner and slide)accept ‘air resistance’ or ‘drag’ for friction
1
(due to the) slide not (being perfectly) smoothaccept miners clothing is rough
or
causing (kinetic) energy to be transferred as heat/internal energy of surroundingsaccept lost/transformed for transferredaccept air for internal energy of surroundings
1[8]
Q5.
GCSE Physics Revision: 1) Energy V1(a) (i) (dismantle and) remove radioactive waste / materials / fuels
accept nuclear for radioactivedo not accept knock down / shut down
1
(ii) increases it do not accept it has a negative effect
1
(b) (i) if efficiency is not mentioned it must be impliedanswers in terms of energygenerated only gains no credit
K most efficientorM least efficient
accept K and / or L are more efficient than M1
(efficiency) of K and L increases, (efficiency) of M (almost) constant /slightly reduced
all 3 power stations must be mentioned to get this mark1
(ii) any two from:
• do not know how many (nuclear) power stations there will be
• power stations may continue to increase in efficiency
• do not know what type of power station new ones will beaccept new methods may be found to generate electricity / energyaccept other ways of generating energy may be expanded
• do not know future energy / electricity demandsaccept we may become more energy efficient
• may be new uses for uranium2
[6]
Q6.(a) (i) produces carbon dioxide / nitrogen oxides
accept greenhouse gasesignore pollutant gases
1
that (may) contribute to global warmingaccept causes global warmingdamages ozone layer negates this markaccept alternative answers in terms of: sulfur dioxide / nitrogen oxides causing acid rain
1
(ii) carbon capture / storage
GCSE Physics Revision: 1) Energy V1answer must relate to part (a)(i)collecting carbon dioxide is insufficient
or
plant more trees
or
remove sulfur (before burning fuel)1
(b) (i) (power station can be used) to meet surges in demandaccept starts generating in a short timecan be switched on quickly is insufficient
1
(ii) can store energy for later use accept renewable (energy resource)accept does not produce CO2 / SO2 / pollutant gases
1
(c) (i) turbines do not generate at a constant rateaccept wind (speed) fluctuatesaccept wind is (an) unreliable (energy source)
1
(ii) any one from:
• energy efficient lighting (developed / used)use less lighting is insufficient
• increased energy cost (so people more likely to turn off)accept electricity for energy
• more people becoming environmentally aware1
[7]
Q7.(a) water moves (from a higher level to a lower level)
1
transferring GPE to KE1
rotating a turbine to turn a generatoraccept driving or turning or spinning for rotatingmoving is insufficient
1
transferring KE to electrical energytransferring GPE to electrical energy gains 1 mark of the 2 marks available for energy transfers
1
(b) (TVs in stand-by) use electricity
GCSE Physics Revision: 1) Energy V1accept power / energy
1
generating electricity (from fossil fuels) produces CO2
accept greenhouse gasaccept sulfur dioxide
1
(CO2) contributes to global warmingaccept climate change for global warmingaccept greenhouse effect if CO2 givenaccept acid rain if linked to sulfur dioxide
1
(c) a factor other than scientific is given, eg economic, political or legalpersonal choice is insufficient
1[8]
Q8.(a) a value of 1°C or less
reason only scores if a correct value for the resolution is givendo not allow 0 / zero
1
temperatures in investigation are recorded to the nearest degree (Celsius)
or
differences between temperature rises for different materials is greater than 1°C
1
(b) any one from:
• room temperature / start temperature (of material)• type of insulation• thickness of insulation• time that cylinder was heated for• the power output of the immersion heater
allow amount1
(c) aluminiumreason only scores if ‘aluminium’ is given
1
smallest temperature riseallow smaller temperature rise (than the other metals)accept justification by calculation
1
(d) 500(J / kg °C)allow temperature increase = 18 °C for 1 markcorrect substitution 18000 = 2 x c x 18 gains 2 marks
GCSE Physics Revision: 1) Energy V1provided no subsequent steporcorrect substitution and rearrangementc = 18000 / (2 x 18) gains 2 marks provided no subsequent stepallow 2 marks for 474 (J / kg °C) (a SHC calculated using a temperature of 19 °C)allow 1 mark for substitution 18000 = 2 x c x 19 provided no subsequent steporsubstitution and rearrangementc = 18000 / (2 x 19) provided no subsequent stepallow 2 marks for a SHC calculated using a temperature increase of an incorrect metal, ie900 (J / kg °C for aluminium)391 (J / kg °C for copper)450 (J / kg °C for iron)134 (J / kg °C for lead)
3[8]
Q9.(a) gravity (of moon and sun)
1
(b) any two from:1 mark for statement, 1 mark for correctly linked reason
• tidal energy is renewable (1)• so won’t run out like fossil fuels (1)
or
• doesn’t emit carbon dioxide• so won’t contribute to global warming / climate change
or
• doesn’t emit oxides of sulfur or nitrogen• so doesn’t cause acid rain
or
• doesn’t use fossil fuels• so less impact on environment of extraction / transport
or
• doesn’t produce particulates• so less effect on health / environment
Max. 4
(c) coal consumption per year = 29.25 × 1000 × 6 million = 175 500 000 000 MJ1
1 hectare of willow will produce 9 × 13 × 1000 = 117 000 MJ per year1
GCSE Physics Revision: 1) Energy V1so need 175 500 000 000 ÷ 117 000 = 1 500 000 (hectares)
1
allow 1 500 000 with no working shown for 3 marks
(d) although has higher direct emissions than other fuels1
it has much lower lifetime emissions1
[10]
GCSE Physics Revision: 1) Energy V1
Examiner reports
Q1.(a) (i) Only about one third of the students were able to answer this question
correctly, although most attempted a calculation. The problem would appear to be that most students did not realise which of the energy sources were fossil fuels. The most common answer was 93%, i.e. adding up all of the energy sources apart from renewable.
(ii) Most students were able to identify oil as being the energy source that is not renewable.
(b) About half of the students knew that fossil fuels are burned to heat water.
(c) Although most of the students knew that carbon dioxide causes global warming, some thought that carbon dioxide is the main cause of acid rain.
Q4.
(a) This question was well done with nearly all of the students scoring both marks.
(b) This question was not well answered for a variety of reasons. Some students simply did not know where to start, whilst others tried using momentum. Also, many realised the need to use the equation for kinetic energy, but were then unable to transform it or failed to square root; 300 was a common incorrect answer. Few students stated that GPE = KE although they used their answer from part (a) in the calculation. Only a tenth of students were able to complete the calculation and give an answer with an appropriate number of significant figures.
(c) Most students scored one mark for mentioning friction, but very few students were able to give a complete explanation to score all three marks. The idea that work would be done against friction was hardly ever mentioned. A significant number of students thought that the reduced maximum speed was due to the change in angle of the slide and the slide becoming horizontal.
Q5.
(a) (i) There were few correct answers, most candidates referred to closing down the power station but few discussed the removal of radioactive material from the site.
(ii) A mix of answers with many candidates attempting to give a reason.
(b) (i) A large number of answers failed to mention the efficiency, which is what the question was about. Of those candidates which did, some compared the efficiency of the three power stations to each other, some discussed the change in efficiency of each power station over the years, but very few gave both answers.
(ii) A large number of vague answers were seen, such as ‘anything could happen in the future’ or ‘we can’t predict that far into the future’. Just over half of the candidates scored at least 1 mark.
GCSE Physics Revision: 1) Energy V1Q6.
(a) (i) This was generally well answered with over half of the students scoring both marks. The most common answers were related to carbon dioxide and global warming.
(ii) There were some good answers describing carbon capture methods. However, a significant number of students failed to take notice of the statement that ‘the amount of fossil fuels burnt stays the same’ and gave answers relating to reducing the amount of fossil fuels burnt.
(b) (i) This was well answered by over half of the students. A common error was to state what a ‘short start-up time’ was, rather than explaining its importance.
(ii) Over half of the students scored the mark here, the most common answer being ‘renewable’, with a minority realising the significance of it being a way to store energy for use at a later time.
(c) (i) This was well answered by nearly two-thirds of students. It appeared that a significant number of students did not understand the word ‘fluctuations’.
(ii) Again this was well answered, the most common response referring to the increased use of energy saving light bulbs.
Q7.(a) A very low proportion of students did not attempt this question. Out of those who did
answer nearly one-quarter failed to score any marks; answers referring to burning fossil fuels, wind turbines, waves and tides were not uncommon. Some answers started correctly with water falling, but then reverted to the water being heated up. A significant number of students either failed to include the useful energy transfers taking place, or just referred to the kinetic energy of the moving water transferring to ‘electricity’.
(b) The majority of students were able to gain at least one mark out of the three, with more than one-fifth giving good descriptions of the consequences of burning fossil fuels. Some missed the reference to ‘better for the environment’ and answered in terms of saving money on fuel bills.
(c) Slightly less than half of students scored the mark. Many demonstrated an understanding of legal power made by government, but few mentioned economic factors. Incorrect suggestions included ‘letting the people decide’ or concern about the disposal of appliances which did not comply with the suggested new rule.
Q8.(a) Most students did not understand the term “resolution”. Students who did give a
value of 1 °C or lower frequently wrote “accuracy” as their reason. The reason should have related to the results, but many linked it to the graph scale. Answers of around 67 °C to 70 °C were common as this was the highest value, or it would include all the values shown for all the metals. “10 °C” was less commonly seen, but their reason for this choice was that it was the lowest result. Values of 18 °C to 23 °C were often given because they were the most common or average values for the results. “20 °C” was also seen because that is room temperature.
(b) Less than half of the students could give a control variable. Students who gained the mark often said the type or amount of insulation used. Some said the mass or amount of metal, or the amount of energy transferred, both of which were given in the question. Other responses that were ignored included the surface area, volume
GCSE Physics Revision: 1) Energy V1or colour of the metals, various pieces of apparatus used, such as the thermometer; and some thought that there was water in the cylinder so gave volume of water as a variable.
(c) Just under two thirds of the students gained no marks. The most common answer was lead, with the reason that it had the highest temperature rise. Some students correctly identified aluminium as having the highest specific heat capacity but then said it was due to increasing in temperature by only 10 °C, when a comparative statement was needed. Other students demonstrated a good understanding by going on to explain that, since the rise in temperature was the lowest, this meant the amount of energy required to raise the temperature of 1kg by 1 °C was the highest. A few justified their response by calculating the specific heat capacity of aluminium.
(d) Students should be told that the first mark in a calculation is for the substitution, not for the rearrangement. Many students scored no marks because they did not show their working. In this calculation, 1 mark was given for reading the bar chart, 18°C, and 2 marks for the substitution into the equation, i.e. 18000 = 2 x c x 18. This substitution would gain two thirds of the total marks. There were no further marks for the rearrangement, but 3 marks for the final answer of 500 (J / kg°C). Students who calculated the specific heat capacity for a different metal were awarded 2 marks. Students who misread the increase in temperature as 19°C and used this to calculate the specific heat capacity as 474 (J / kg°C) were also awarded 2 marks.