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)

Why 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.

Metal / Mass of material in kg / Time in minutes / Temperature
in °C / Change in thermal energy in J / Calculated specific heat capacity of material
in 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)

(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.

(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)

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)

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.

(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 fuels.

(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)

(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.

______

(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.

______

(3)

‘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.

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)

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.

(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?

______

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 emissions
in kg per MWh / Lifecycle CO2 emissions
in 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

(ii)Oil

(b) water

accept H2O

[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 out
in a logical manner that could be followed by another person to calculate the specific
heat capacity.

Level 2 (3–4 marks):

The substantive content of a plan is present but may be missing some steps. The plan
may not be in a completely logical sequence but leads towards the calculation of the
specific heat capacity.

Level 1 (1–2 marks):

Simple statements relating to relevant apparatus or steps are made but they may not be
in 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 the
metal

•calculate specific heat capacity

(b) 4 600 = 1 × 657 × temperature change

temperature change = 4 600 / 657

= 7 (°C)

allow 7 with no working shown for 3 marks

(d) heat loss

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

(e) would give a more accurate value or the calculated specific heat capacity will be smaller

because the bubble wrap insulates the material or prevents heat loss

[14]

Q3.

(a) 600 kg = 5880 N

power =

= 4573.3 (W)

this step without the previous steps stated gains 3 marks

% Eff. =

= 57.17 (%)

allow 57.17 with no working shown for 5 marks

(b) gpe = 600 × 9.8 × 35

= 205 800

gpe = KE = ½ m v2

v =

= 26.2 (m / s)

allow 26.2 with no working shown for 6 marks

[11]

Q4.

(a) 13 500 (J)

allow 1 mark for correct substitution, ie 90 x 10 x 15 provided no subsequent step shown

(b) 17
or

correctly calculated and answer given to 2 or 3 significant figures

accept 17.3

allow 2 marks for an answer with 4 or more significant figures, ie 17.32

allow 2 marks for correct substitution, ie 13 500/ their (a) = ½ x 90 x v2

allow 1 mark for a statement or figures showing KE = GPE

(against) friction (between the miner and slide)

accept ‘air resistance’ or ‘drag’ for friction

(due to the) slide not (being perfectly) smooth

accept miners clothing is rough

causing (kinetic) energy to be transferred as heat/internal energy of surroundings

accept lost/transformed for transferred

accept air for internal energy of surroundings

[8]

Q5.

(a)(i)(dismantle and) remove radioactive waste / materials / fuels

accept nuclear for radioactive

do not accept knock down / shut down

(ii)increases it

do not accept it has a negative effect

(b)(i)if efficiency is not mentioned it must be implied

answers in terms of energy

generated only gains no credit

K most efficient
or
M least efficient

accept K and / or L are more efficient than M

(efficiency) of K and L increases, (efficiency) of M (almost) constant /
slightly reduced

all 3 power stations must be mentioned to get this mark

(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 be

accept new methods may be found to generate electricity / energy

accept other ways of generating energy may be expanded

•do not know future energy / electricity demands

accept we may become more energy efficient

•may be new uses for uranium

[6]

Q6.

(a) (i)produces carbon dioxide / nitrogen oxides

accept greenhouse gases

ignore pollutant gases

that (may) contribute to global warming

accept causes global warming

damages ozone layer negates this mark

accept alternative answers in terms of: sulfur dioxide / nitrogen oxides causing acid rain

(ii)carbon capture / storage

answer must relate to part (a)(i)

collecting carbon dioxide is insufficient

plant more trees

remove sulfur (before burning fuel)

(b) (i) (power station can be used) to meet surges in demand

accept starts generating in a short time

can be switched on quickly is insufficient

(ii)can store energy for later use

accept renewable (energy resource)

accept does not produce CO2 / SO2 / pollutant gases

accept wind (speed) fluctuates
accept wind is (an) unreliable (energy source)

(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 aware

[7]

Q7.

(a) water moves (from a higher level to a lower level)

transferring GPE to KE

rotating a turbine to turn a generator

accept driving or turning or spinning for rotating

moving is insufficient

transferring KE to electrical energy

transferring GPE to electrical energy gains 1 mark of the 2 marks available for energy transfers

(b) (TVs in stand-by) use electricity

accept power / energy

generating electricity (from fossil fuels) produces CO2

accept greenhouse gas

accept sulfur dioxide

(CO2) contributes to global warming

accept climate change for global warming

accept greenhouse effect if CO2 given

accept acid rain if linked to sulfur dioxide

personal choice is insufficient

[8]

Q8.

(a) a value of 1°C or less

reason only scores if a correct value for the resolution is given

do not allow 0 / zero

temperatures in investigation are recorded to the nearest degree (Celsius)

differences between temperature rises for different materials is greater than 1°C

(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 amount

(c)aluminium

reason only scores if ‘aluminium’ is given

smallest temperature rise

allow smaller temperature rise (than the other metals)

accept justification by calculation

(d) 500(J / kg °C)

allow temperature increase = 18 °C for 1 mark

correct substitution 18000 = 2 x c x 18 gains 2 marks provided no subsequent step

correct substitution and rearrangement

c = 18000 / (2 x 18) gains 2 marks provided no subsequent step

allow 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 step

substitution and rearrangement

c = 18000 / (2 x 19) provided no subsequent step

allow 2 marks for a SHC calculated using a temperature increase of an incorrect metal, ie
900 (J / kg °C for aluminium)
391 (J / kg °C for copper)
450 (J / kg °C for iron)
134 (J / kg °C for lead)

[8]

Q9.

(a) gravity (of moon and sun)

(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)

•doesn’t emit carbon dioxide

•so won’t contribute to global warming / climate change

•doesn’t emit oxides of sulfur or nitrogen

•so doesn’t cause acid rain

•doesn’t use fossil fuels

•so less impact on environment of extraction / transport

•doesn’t produce particulates

•so less effect on health / environment

Max. 4

1 hectare of willow will produce 9 × 13 × 1000 = 117 000 MJ per year

so need 175 500 000 000 ÷ 117 000 = 1 500 000 (hectares)

allow 1 500 000 with no working shown for 3 marks

(d) although has higher direct emissions than other fuels

it has much lower lifetime emissions

[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.