energy transfers (particle theory, conduction, convection...

Energy transfers (Particle theory, conduction, convection, IR, evaporation)

188 minutes

188 marks

of 72

Q1. (a) The diagrams, X, Y and Z, show how the particles are arranged in the three states of matter.

(i) Which one of the diagrams, X, Y or Z, shows the arrangement of particles in a liquid?

(1)

(ii) Which one of the diagrams, X, Y or Z, shows the arrangement of particles in a gas?

(1)

(b) Draw a ring around the correct answer in each box to complete each sentence.

(1)

vibrating in fixed positions.

(i) In a gas, the particles are moving randomly.

not moving.

the particles in a liquid. (1)

stronger than

(ii) In a solid, the forces between the particles are equal to the forces between

weaker than

Write the correct answer in the box.


of 72

(c) The picture shows a puddle of water in a road, after a rain shower.

(i) During the day, the puddle of water dries up and disappears. This happens because the water particles move from the puddle into the air.

What process causes water particles to move from the puddle into the air?

Draw a ring around the correct answer.

(1)

condensation evaporation radiation

(ii) Describe one change in the weather which would cause the puddle of water to dry up faster.

...............................................................................................................

............................................................................................................... (1)

(Total 6 marks)

of 72

Q2. According to kinetic theory, all matter is made up of small particles. The particles are constantly moving.

Diagram 1 shows how the particles may be arranged in a solid.

Diagram 1

(a) One kilogram of a gas has a much larger volume than one kilogram of a solid.

Use kinetic theory to explain why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (4)

(b) Diagram 2 shows the particles in a liquid. The liquid is evaporating.

Diagram 2

(i) How can you tell from Diagram 2 that the liquid is evaporating?

...............................................................................................................

............................................................................................................... (1)

of 72

(ii) The temperature of the liquid in the container decreases as the liquid evaporates.

Use kinetic theory to explain why.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (3)

(Total 8 marks)

Q3. A student did two experiments on radiation. The apparatus he used is shown in the diagram.

Experiment 1

• The student put the same volume of cold water into the two cans. • He then switched on the heater. • Ten minutes later the water in the can with the dull black surface was much hotter than the

water in the other can.

of 72

Experiment 2

• The student filled both cans with boiling water. • This time he left the heater off. • Ten minutes later the water in the can with the dull black surface was much cooler than

the water in the other can.

Use words from the box to complete the sentences.

absorber conductor emitter reflector

Experiment 1 shows that the dull black surface is a good ........................... of radiation and that

the shiny silver surface is a good ......................... of radiation.

Experiment 2 shows that the dull black surface is a good ................................... of radiation. (Total 3 marks)

Q4. The diagrams show the cross-section of three double glazed windows.

The gap between the two sheets of glass can be filled with either air or a mixture of air and argon.

The U-values for different types of double glazed windows, using different types of glass X and Y, are given in the table.

Type of window 12 mm

gap 16 mm

gap 20 mm

gap

1 Glass type X with air 2.9 2.7 2.8

2 Glass type X with air and argon 2.7 2.6 2.6

3 Glass type Y with air 1.9 1.8 1.8

4 Glass type Y with air and argon 1.6 1.5 1.5

of 72

(a) Which type of window, 1, 2, 3 or 4 is the least energy efficient?

........................................................................................................................ (1)

(b) Which two windows should be compared to decide if adding argon to the gap improves the energy efficiency of the window?

........................................................................................................................ (1)

(c) A householder is going to buy new windows. The sales assistant recommends that the householder buys windows with a 20 mm gap. These windows are much more expensive than those with a 16 mm gap.

It is not worth the householder paying the extra cost to buy 20 mm windows rather than 16 mm windows.

Explain this in terms of energy efficiency.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(d) Windows are given an energy rating, from A down to G. The diagram shows the energy label from one type of double glazed window.

All new double glazed windows must have an energy rating of C or above. Windows having a C rating have a U-value of 1.9.

Which windows given in the table would the householder be unable to buy?

........................................................................................................................ (1)

of 72

(e) Glass transmits infrared radiation and visible light. The amount transmitted depends on the type and thickness of the glass. The data from tests on two different types of glass is displayed in the graph below.

A homeowner has a glass conservatory built on the back of the house. The homeowner tells the builder that the inside of the conservatory should stay as cool as possible throughout the summer.

Explain why the builder uses ‘Type B’ glass for the conservatory.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 7 marks)

of 72

Q5. The drawing shows parts of a house where it is possible to reduce the amount of energy lost.

(a) Give one way in which the amount of energy lost can be reduced from each of the following parts of the house.

1, 2 and 4 ....................................................................................................................

5 ..................................................................................................................................

7 .................................................................................................................................. (3)

(b) Energy consumption can be reduced by using a more efficient boiler or more efficient light bulbs.

What is meant by a more efficient light bulb?

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 4 marks)

of 72

Q6. The picture shows one type of solar water heater. Water from the tank is slowly pumped through copper pipes inside the solar panel where the water is heated by energy from the Sun.

(a) Explain why the copper pipes inside the solar panel are painted black.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(b) Each day the average European family uses 100 kg of hot water. To kill bacteria, the water going into the tank at 20 °C must be heated to 60 °C.

Calculate the energy needed to increase the temperature of 100 kg of water by 40 °C.

Specific heat capacity of water = 4200 J/kg °C.

Write down the equation you use, and then show clearly how you work out your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

Energy transferred = .................................... J (2)

of 72

(c) The bar chart shows how the amount of solar energy transferred to the water heater varies throughout the year.

How many months each year will there not be enough solar energy to provide the hot water used by an average European family?

.................................................. months (1)

of 72

(d) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

The water in the tank could be heated by using an electric immersion heater.

Outline the advantages and disadvantages of using solar energy to heat the water rather than using an electric immersion heater.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (6)

(Total 11 marks)

Q7. The drawing shows water being heated in a metal saucepan.

(a) Explain, in terms of the particles in the metal, how heat energy is transferred through the base of the saucepan.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

of 72

(b) Energy is transferred through the water by convection currents. Explain what happens to cause a convection current in the water. The answer has been started for you.

As heat energy is transferred through the saucepan, the water particles at the bottom

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(c) Some energy is transferred from the hotplate to the air by thermal radiation. What is meant by thermal radiation?

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 6 marks)

of 72

Q8. Power stations are usually not very efficient. A lot of energy is wasted as thermal energy. The diagrams show the percentage of energy transferred by two coal-burning power stations.

(a) Write the two missing figures in the boxes on the diagrams. (2)

(b) Which power station is the most efficient overall, the normal power station or the combined heat and power station? Give reasons for your answer.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

of 72

(c) Some heat energy released from burning coal on an open fire is emitted by radiation. Tick () the main type of electromagnetic radiation emitted by hot coal.

(1)

Type of electromagnetic radiation

Tick ( )

gamma

infra red

ultraviolet

X-ray

(d) Radiation can be reflected or absorbed when it strikes a surface. What type of surface is a poor reflector but a good absorber of radiation?

.....................................................................................................................................

..................................................................................................................................... (1)

(Total 6 marks)

Q9. The diagram shows a side view of a double-glazed window.

of 72

(a) Use each of the terms in the box to explain how heat is lost from inside a house through the window.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

conduction convection radiation

(b) Besides heat, state one other form of energy that passes through double-glazed windows.

..................................................................................................................................... (1)

(c) Explain why plastic foam cavity wall insulation cuts down energy transfer between warm inner walls and cooler outer walls.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(d) When it rains the walls and windows of a house get wet.

Explain how the drying process can increase the cooling of the house.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 8 marks)

of 72

Q10. (a) The diagram shows how much heat is lost each second from different parts of an uninsulated house.

(i) Each year, the house costs £760 to heat.

How much money is being wasted because of heat lost through the roof?

Show clearly how you work out your answer.

..........................................................................................................................

.......................................................................................................................... (2)

(ii) Insulating the loft would cut the heat lost through the roof by 50 %.

The loft insulation has a payback time of years.

How much did the loft insulation cost to buy?

..........................................................................................................................

Cost of loft insulation = £ ................................................. (1)

(b) What happens to the wasted energy?

....................................................................................................................................

.................................................................................................................................... (1)

(Total 4 marks)

of 72

Q11. (a) The diagram shows an immersion heater used to heat water inside a tank. Heat is transferred through the water by convection.

(i) Draw arrows on the diagram to show the movement of the water in the tank when the heating element is switched on.

(2)

(ii) Explain how a convection current is set up in the water. The explanation has been started for you.

When the heating element is switched on, the hot water nearest the element rises

because ...........................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(b) The diagram shows two ways to reduce heat loss through the walls of a house.

(i) How is the aluminium foil able to reduce heat loss?

..........................................................................................................................

.......................................................................................................................... (1)

of 72

(ii) The plastic foam is good at reducing heat loss through the walls. Explain why.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (3)

(c) Evaporation is an important heat transfer process. When sweat evaporates, it takes heat energy from your body. As humidity increases, you are more likely to feel hot and uncomfortable. Explain why.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 10 marks)

Q12. (a) The diagram shows two switches on a room heater. The heater has three power settings. The power produced by two of the settings is given in the table.

(i) When both switches are on, the heater works at the high power setting.

What is the power of the heater when it is switched to the high power setting?

...............................................................................................................

Power = ......................................................... kW (1)

Setting Power in kW

Low 0.5

Medium 1.5

High

of 72

(ii) The heater is used on the medium power setting. It is switched on for three hours.

Use the equation in the box to work out the energy transferred from the mains to the heater in three hours.


...............................................................................................................

...............................................................................................................

Energy transferred = ..................................... kWh (2)

energy transferred (kilowatt-hour, kWh) =

power (kilowatt, kW) ×

time (hour, h)

(iii) Electricity costs 12 pence per kilowatt-hour.

Use the equation in the box to calculate how much the heater costs to use on medium power for three hours.


...............................................................................................................

...............................................................................................................

Total cost = ................................................ pence (2)

total cost = number of kilowatt-hours × cost per kilowatt-hour

of 72

(b) The heater is used to warm a room.

The graph shows how the temperature of the room changes from the moment the heater is switched on.

The heater was first used on the medium setting.

(i) At what time was the heater setting changed to the high setting?

..............................................................

Give a reason for your answer.

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(ii) From 7 pm until 10 pm, the temperature of the room is not changing.

Which one of the following statements gives the reason why the temperature of the room is not changing?

Put a tick ( ) in the box next to your answer.

(1) (Total 8 marks)

The room is losing energy slower than the heater supplies energy.

The room is losing energy as fast as the heater supplies energy.

The room is losing energy faster than the heater supplies energy.

of 72

Q13. (a) The diagram shows two switches on a room heater. The heater has three power settings. The power produced by two of the settings is given in the table.

(i) When both switches are on, the heater works at the high power setting.

What is the power of the heater, in kilowatts, when it is switched to the high power setting?

...............................................................................................................

Power = ......................................................... kilowatts (1)

Setting Power in

watts

Low 700

Medium 1400

High

(ii) The heater is used on the high power setting. It is switched on for 1½ hours.

Use the equation in the box to work out the energy transferred from the mains to the heater in 1½ hours.

Show clearly how you work out your answer and give the unit.

...............................................................................................................

...............................................................................................................

...............................................................................................................

Energy transferred = .................................................... (3)

energy transferred = power × time

(iii) This type of heater is a very efficient device.

What is meant by a device being very efficient?

...............................................................................................................

............................................................................................................... (1)

of 72

(b) The graph shows how the temperature of a room changes during the 1½ hours that the heater is used.

After 1 hour, the temperature of the room has become constant, even though the heater is still switched on.

Explain why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 7 marks)

of 72

Q14. The diagram shows a car radiator. The radiator is part of the engine cooling system.

Liquid coolant, heated by the car engine, enters the radiator. As the coolant passes through the radiator, the radiator transfers energy to the surroundings and the temperature of the coolant falls.

(a) Why is the radiator painted black?

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

of 72

(b) Different radiators have different numbers of cooling fins along the length of the radiator.

The sketch graph shows how the number of cooling fins affects the rate of energy transfer from the radiator.

The number of cooling fins affects the rate of energy transfer from the radiator.

Explain how.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) When the car engine is working normally, 2 kg of coolant passes through the radiator each second. The temperature of the coolant falls from 112 °C to 97 °C.

Calculate the energy transferred each second from the coolant.

Specific heat capacity of the coolant = 3800 J/kg °C.

Use the correct equation from the Physics Equations Sheet.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

Energy transferred each second = .............................................................. J (3)

of 72

(d) On cold days, some of the energy transferred from a hot car engine is used to warm the air inside the car. This is a useful energy transfer.

What effect, if any, does this energy transfer have on the overall efficiency of the car engine?



........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 9 marks)

decreases the

efficiency does not change the

efficiency increases the

efficiency

Q15. The diagram shows the equipment a student used to investigate how the colour of a surface affects how fast it emits (gives out) heat.

An equal volume of boiling water was poured into each metal can. The student then recorded the temperature of the water in each can every minute for ten minutes.

(a) (i) Which of the following was a control variable in this investigation?


The volume of boiling water.

The decrease in temperature of the water.

The outside colour of the metal can.

of 72

(ii) Give one advantage of using a temperature sensor and datalogger rather than a thermometer to measure the temperature of the water.

...............................................................................................................

............................................................................................................... (1)

(b) The student’s results for both cans are plotted on the graph.

Which line, A or B, shows how the temperature of the water inside the black-coloured metal can changed?

Draw a ring around your answer. A B

Explain the reason for your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(c) Some gardeners make soil darker by digging black soot into the soil. Other gardeners use straw to protect plants from the cold.

(i) Complete the following sentence by drawing a ring around the correct line in the box.

On a warm day, the temperature of darker coloured soil will increase

(1)

slower than

as fast as the temperature of lighter coloured soil.

faster than

of 72

(ii) Give a reason for your answer to part (c)(i).

...............................................................................................................

............................................................................................................... (1)

(iii) The statement in the box is false.

Change one word in the statement to make the statement true.

Write down your new statement. The answer has been started for you.

This is because air is a ............................................................................ (1)

(Total 7 marks)

Straw keeps plants warm by trapping air. This is because air is a good conductor.

Q16. A vacuum flask is designed to reduce the rate of heat transfer.

of 72

(a) (i) Complete the table to show which methods of heat transfer are reduced by each of the features labelled in the diagram.

The first row has been done for you.

(2)

(ii) Explain why the vacuum between the glass walls of the flask reduces heat transfer by conduction and convection.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

Feature Conduction Convection Radiation

vacuum

silvered surfaces

plastic cap

(b) The diagram shows a gas flame patio heater.

(i) Explain why the top surface of the reflecting hood should be a light, shiny surface rather than a dark, matt surface.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

of 72

(ii) Most of the chemical energy in the gas is transformed into heat. A small amount of chemical energy is transformed into light.

Draw and label a Sankey diagram for the patio heater.

(2)

(iii) State why the total energy supplied to the patio heater must always equal the total energy transferred by the patio heater.

...........................................................................................................................

........................................................................................................................... (1)

(Total 9 marks)

Q17. The diagram shows the direction of heat transfer through a single-glazed window.

(a) (i) Name the process by which heat is transferred through the glass.

............................................................................................................... (1)

(ii) Explain how heat is transferred through the glass.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

of 72

(b) The rate of heat transfer through a window depends on the difference between the inside and outside temperatures.

The graph shows the rate of heat transfer through a 1 m2 single-glazed window for a range of temperature differences.

(i) What is the range of temperature differences shown in the graph?

From ................................................ to ................................................ (1)

(ii) A student looks at the graph and concludes:

‘Doubling the temperature difference doubles the rate of heat transfer.’

Use data from the graph to justify the student’s conclusion.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

of 72

(iii) A house has single-glazed windows. The total area of the windows in the house is 15 m2.

On one particular day, the difference between the inside and outside temperatures is 20 °C.

Use the graph to calculate the total rate of heat transfer through all of the windows on this particular day.


...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................

Rate of heat transfer = ........................................ J/s (2)

(c) A homeowner plans to replace the single-glazed windows in his home with double-glazed windows. He knows that double-glazed windows will reduce his annual energy bills.

The table gives information about the double glazing to be installed by the homeowner.

Explain, in terms of energy savings, why replacing the single-glazed windows with these double-glazed windows is not cost effective.

To gain full marks you must complete a calculation.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 10 marks)

Cost to buy and install Estimated yearly savings on energy bills

Estimated lifetime of the double-glazed windows

£5280 £160 30 years

of 72

Q18. The diagram shows a metal pan being used to heat water.

Energy from the gas flame is transferred through the metal pan by conduction.

Explain the process of conduction through metals.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (4)

(Total 4 marks)

Q19. A student has read that a solar cell with a dirty surface will not work as well as a solar cell with a clean surface.

To test the effect of a dirty surface on a solar cell, the student set up the following equipment.

of 72

The student put the desk lamp a fixed distance from the solar cell. To represent the effect of a dirty surface, the student covered the surface of the solar cell with pieces of tracing paper. Each time the student added a piece of paper, she measured the output voltage of the solar cell.

(a) The results taken by the student have been used to draw the graph below.

(i) One of the results seems to be anomalous.

Draw a ring around the anomalous data point on the graph. (1)

(ii) The larger the number of sheets of tracing paper used, the lower the intensity of the light reaching the solar cell.

Draw a ring around the correct answer in the box to complete the sentence.

(1)

a decrease in

A decrease in the intensity of the light reaching the solar cell causes no change to

an increase in

of 72

the output voltage from the solar cell.

(b) People can buy panels of solar cells to generate electricity for their homes. Any surplus electricity can be sold to the electricity supply company.

(i) Give one environmental advantage of generating electricity using solar cells rather than generating electricity in a coal-burning power station.

........................................................................................................................

........................................................................................................................ (1)

(ii) A homeowner pays £7600 to have solar panels fitted on the roof of their house. The homeowner expects to save £950 each year from reduced energy bills and from selling the electricity.

Assuming these figures to be correct, calculate the pay-back time for the solar panels.


........................................................................................................................

........................................................................................................................

........................................................................................................................

Pay-back time = .................................................. years (2)

(iii) Draw a ring around the correct answer in the box to complete the sentence.

the pay-back time. (1)

decrease

Allowing the surface of the solar panels to become very dirty will not change

increase

(iv) Explain your answer to part (b)(iii).

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 8 marks)

of 72

Q20. The diagram shows a simple type of portable shower. The water container is a strong plastic bag that is black on one side and white on the other. To warm the water, the bag is placed on the ground in direct sunlight, with the black side facing the Sun.

(a) (i) Name the process by which heat is transferred from the Sun to the outside of the bag.

............................................................................................................... (1)

(ii) Explain why the black side of the bag and not the white side should face the Sun.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

of 72

(b) The graph shows how the temperature of the water inside a full bag increases after the bag is placed outside on a sunny day.

(i) How long does it take for the water to reach 37 °C?

............................................ (1)

(ii) Describe how the temperature of the water changes during the three hours.

...............................................................................................................

............................................................................................................... (1)

(c) A different manufacturer makes the same type of portable shower but uses a bag with a larger surface area. The bag is made from the same coloured plastics and holds the same amount of water.

(i) To compare the efficiency of the two bags at heating water, several variables need to be controlled.

Name two variables that need to be controlled.

1 ............................................................................................................

2 ............................................................................................................ (2)

(ii) The second bag has a larger surface area. Draw a line on the graph to show how the temperature of the water inside the second bag would change over the first hour. Assume that the two bags are tested in exactly the same way.

(1) (Total 8 marks)

of 72

Q21. (a) Use the words from the box to complete the following sentences.

(i) The transfer of thermal energy (heat) by the movement of hot liquids

is called ............................................. . (1)


(ii) The transfer of thermal energy (heat) from one particle to another

is called ............................................. . (1)

of 72

(b) A student set up the following equipment. The 3 metal plates are the same distance from the heater. The surfaces of each of the 3 metal plates are different colours.

The student switched the heater on for 10 minutes. The thermometers were read before the heater was switched on. The thermometers were read again just after the heaters were switched off. The readings are shown in the table.

(i) Which set of readings, 1, 2 or 3, is most likely to have been taken from the thermometer labelled L?

........................................


...............................................................................................................

............................................................................................................... (2)

Temperature before switching on in °C

Temperature after switching on in °C

1 19 21

2 19 29

3 19 23

of 72

(ii) Which one of the following was not a control variable in this experiment?


the distance between the heater and the metal plates

the power of the heater

the temperature before the heater was switched on

(1)

the colour of the metal plates

(iii) Suggest one advantage of using a temperature sensor, data logger and computer, rather than a thermometer to carry out this experiment.

...............................................................................................................

............................................................................................................... (1)

(c) The picture shows a fire fighter putting out a forest fire. The fire fighter’s clothing has thick thermal padding inside and a light coloured, fire proof, shiny layer outside.

(i) What is the main way that heat is transferred through the air from the fire to the fire fighter?

...............................................................................................................

............................................................................................................... (1)

of 72

(ii) Why is the outside layer of the clothing shiny?

...............................................................................................................

............................................................................................................... (1)

(d) The graph shows the result of a laboratory test on two types of thermal padding. Each type of padding was put onto a very hot metal surface and the temperature inside the padding was taken every minute.

Which type of padding, M or N, would it be best to use inside the fire fighter’s clothing?

..........................................................................................


........................................................................................................................

........................................................................................................................ (1)

(Total 9 marks)

of 72

Q22. The diagram shows the design of a solar cooker. The cooker heats water using infrared radiation from the Sun.

(a) Why is the inside of the large curved dish covered with shiny metal foil?

........................................................................................................................

........................................................................................................................ (1)

(b) Which would be the best colour to paint the outside of the metal cooking pot?



........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

black silver white

(c) Why does the cooking pot have a lid?

........................................................................................................................

........................................................................................................................ (1)

of 72

(d) Calculate how much energy is needed to increase the temperature of 2 kg of water by 80 °C.

The specific heat capacity of water = 4200 J/kg °C.

Use the correct equation from the Physics Equations Sheet.

........................................................................................................................

........................................................................................................................

........................................................................................................................

Energy = ...................................................................... J (2)

(Total 6 marks)

Q23. The vacuum flask shown has five features labelled, each one designed to reduce heat transfer.

(a) (i) Which labelled feature of the vacuum flask reduces heat transfer by both conduction and convection?

........................................................................................................................ (1)

of 72

(ii) Explain how this feature reduces heat transfer by both conduction and convection.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(b) (i) Which labelled feature of the vacuum flask reduces beat transfer by radiation?

........................................................................................................................ (1)

(ii) Explain how this feature reduces heat transfer by radiation.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 6 marks)

of 72

Q24. The diagram shows two thermometers. The bulb of each thermometer is covered with a piece of wet cotton wool. One of the thermometers is placed in the draught from a fan.

The graph shows how the temperature of each thermometer changes with time.

of 72

(a) Which of the graph lines, A or B, shows the temperature of the thermometer placed in the draught?

Explain, in terms of evaporation, the reason for your answer.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (3)


(b) A wet towel spread out and hung outside on a day without wind dries faster than an identical wet towel left rolled up in a plastic bag.

Explain why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 5 marks)

of 72

Q25. (a) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

The diagram shows the structure of a vacuum flask.

A vacuum flask is designed to reduce the rate of energy transfer by heating processes.

Describe how the design of a vacuum flask keeps the liquid inside hot.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (6)

of 72

(b) Arctic foxes live in a very cold environment.

© Purestock/Thinkstock

Arctic foxes have small ears.

How does the size of the ears help to keep the fox warm in a cold environment?

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 8 marks)

Q26. The diagram below shows a house which has not been insulated. The cost of the energy lost from different parts of the house during one year is shown on the diagram.

of 72

(a) The total cost of the energy lost during one year is £1000.

(i) What is the cost of the energy lost through the floor?

........................................................................................................................... (2)

(ii) Suggest one way of reducing this loss.

........................................................................................................................... (1)

(b) The table below shows how some parts of the house may be insulated to reduce energy losses. The cost of each method of insulation is also given.

WHERE LOST COST OF ENERGY LOST PER YEAR (£)

METOD OF INSULATION

COST OF INSULATION (£)

roof 250 fibre-glass in loft 300

walls 350 foam filled cavity 800

windows 100 double glazing 4500

doors 150 draught proofing 5

(i) Which method of insulation would you install first? Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii) Which method of insulation would you install last? Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(Total 9 marks)

of 72

M1. (a) (i) Z 1

(ii) X 1

(b) (i) moving randomly 1

(ii) stronger than 1

(c) (i) evaporation 1

(ii) any one from:

• becomes windy

• temperature increases accept (becomes) sunny “the sun” alone is insufficient

• less humid 1

[6]

M2. (a) there are strong forces (of attraction) between the particles in a solid

accept molecules / atoms for particles throughout accept bonds for forces

1

(holding) the particles close together particles in a solid are less spread out is insufficient

1

or

(holding) the particles in a fixed pattern / positions

but in a gas the forces between the particles are negligible accept very small / zero for negligible accept bonds for forces

1

so the particles spread out (to fill their container) accept particles are not close together gas particles are not in a fixed position is insufficient

1

(b) (i) particles are (shown) leaving (the liquid / container) accept molecules / atoms for particles throughout accept particles are escaping particles are getting further apart is insufficient

1

of 72

(ii) accept molecules / atoms for particles throughout accept speed / velocity for energy throughout

particles with most energy leave the (surface of the) liquid accept fastest particles leave the liquid

1

so the mean / average energy of the remaining particles goes down 1

and the lower the average energy (of the particles) the lower the temperature (of the liquid)

1 [8]

M3. absorber 1

reflector 1

emitter 1

[3]

M4. (a) 1 1

(b) 3 and 4 or 1 and 2

1

(c) U-values for the 20 mm windows are the same or higher than those for the 16 mm windows

1

therefore the 20 mm windows are no more energy efficient than 16 mm windows

accept so the 16 mm windows are as energy efficient as 20 mm windows

1

(d) 1 and 2

must have both and no other 1

of 72

(e) Type B glass transmits less infrared than Type A glass accept radiation / heat for infrared accept Type B glass absorbs more infrared than Type A glass

1

and as infrared has a heating effect the conservatory will remain cooler

1 [7]

M5. (a) insulation

allow example e.g fibreglass 1

double glazing allow curtains

1

draught excluder allow double glazing / close fitting door allow turning down thermostat once only / turn down the heating

1

(b) transfers more useful energy allow converts more energy into light / less into heat / less energy wasted

1 [4]

M6. (a) because black is a good absorber of radiation 1

there will be a faster transfer of energy allow the temperature of the water rises faster

1

(b) 16 800 000 allow 1 mark for substitution into correct equation ie 100 × 4200 × 40

2

(c) 7 allow ecf from part (b)

1

of 72

(d) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.

No relevant content. 0 marks

There is a brief description of the advantages and disadvantages of using solar energy to heat the water rather than using an electric immersion heater, including either advantages or disadvantages from the examples below.

Level 1 (1-2 marks)

There is a description of some of the advantages and disadvantages of using solar energy to heat the water rather than using an electric immersion heater, with at least one advantage and one disadvantage from the examples below.

Level 2 (3-4 marks)

There is a clear, balanced and detailed description of the advantages and disadvantages of using solar energy to heat the water rather than using an electric immersion heater, with a minimum of two advantages and two disadvantages from the examples below.

Level 3 (5-6 marks)

examples of the points made in the response

advantages

accept specific examples of polluting gases

• a renewable energy source

• energy is free

• does not pollute the atmosphere

• no fuel is burnt

• energy can be stored (in the water)

disadvantages

accept unreliable energy source

• only available in daylight hours

• availability fluctuates

• insufficient hours of sunlight in some countries

• average low intensity in some countries [11]

of 72

M7. (a) ions / electrons gain (kinetic) energy

accept atom / particles / molecules for ion accept ions vibrate faster accept ions vibrate with a bigger amplitude accept ions vibrate more do not accept ions move faster

1

(free) electrons transfer energy by collision with ions or energy transferred by collisions between vibrating ions

1

(b) move faster or take up more space do not accept start to move / vibrate

1

(warmer) water expands or becomes less dense (than cooler water)

do not accept answers in terms of particles expanding 1

warm water rises (through colder water) or colder water falls to take its place 1

(c) transfer of energy by waves / infrared (radiation) accept rays for waves do not accept transfer of energy by electromagnetic waves ignore reference to heat

1 [6]

M8. (a) 30(%) 1

50(%) 1

(b) combined heat and power station as waste less energy 1

correct reference to 20 % or 70 % accept some energy (50%) is used for heating

1

(c) infra red ticked 1

(d) dark surfaces accept matt / dull / black surfaces

1 [6]

of 72

M9. (a) (heat) is conducted through the glass

the answers must be within the context of the question 1

(heat) passes through glass and air by radiation both glass and air required

1

(heat) crosses the air gap by convection mention of conduction through air is neutral

1

(b) any one from

light accept sunlight

gamma rays

X-rays

radio accept sound or ir or microwaves or electromagnet waves

1

(c) any two from

cuts down convection currents accept stops air moving

air pockets trap air (from moving) accept has air pockets do not accept stops heat moving or traps heat

foam is a poor conductor air in the foam is a good insulator accept air is a good insulator in air pockets for both marks

2

(d) evaporation (of the water) do not accept rain is cold

1

takes energy from the house accept takes heat away or higher energy molecules leave first

1 [8]

M10. (a) (i) £190

nb mention idea of cost per J in £ will come to an approx figure full credit given allow 1 mark for showing that the energy loss through the roof is ¼ of the total energy loss ie 150 / 600

2

of 72

(ii) £142.50 allow ecf 50 % of their (a)(i) × 1.5 ie their (a)(i) × 0.75

1

(b) transferred to surroundings / atmosphere

or becomes spread out 1

[4]

M11. (a) (i) convection current correctly shown with arrows extending to above insulation label line

circulation must show water rising in the left half of the tank accept continuous or broken arrows must be at least one arrow up and one arrow down allow 1 mark for correct diagram which does not extend high enough

2

(ii) it expands or it gets less dense do not allow hot water rises do not accept explanation in terms of molecules expanding or changing density do not accept lighter or heavier

1

more dense water falls allow cold water falls if qualified with a suitable reason

1

(b) (i) reflects heat back into the room or where it came from

accept infrared or radiation or energy for heat accept bounce for reflect if in correct context

1

(ii) air is a (good) insulator or poor conductor or air stops conduction

do not accept plastic foam is a good insulator or bad conductor 1

air is trapped 1

convection loss reduced or stopped 1

(c) two out of the following three:

any answer which gains credit must contain a comparison

rate of evaporation decreases accept less sweat can evaporate or evaporation is more difficult

of 72

less heat energy removed from the body

higher humidity the less water vapour can be absorbed (into the air) accept sweat for water vapour do not credit description of high humidity accept a correct answer in terms of dynamic equilibrium

2 [10]

M12. (a) (i) 2(.0)

accept 2000 W or 2000 watt(s) accept answer given in table do not accept 2000

1

(ii) 4.5 allow 1 mark for correct substitution ie 1.5 × 3 allow 1 mark for the answers 1.5 or 6(.0)

2

(iii) 54 or their (a)(ii) × 12 correctly calculated

allow 1 mark for correct substitution ie 4.5 × 12 or their (a)(ii) × 12 allow 1 mark if correct answer is given in pounds eg £54

2

(b) (i) 6 pm 1

temperature starts to rise faster only scores if 6 pm given

or graph (line) is steeper / steepest

it refers to graph gradient or temperature accept answers in terms of relative temperature rise eg 5 to 6 pm 2 °C rise, 6 to 7 pm 6 °C rise accept temperature rises sharply / rapidly / quickly do not accept temperature starts to rise

1

(ii) middle box ticked 1

[8]

of 72

M13. (a) (i) 2.1

correct answer only 1

(ii) 3.15 or their (a)(i) × 1.5 correctly calculated

allow 1 mark for correct substitution ie 2.1 × 1.5 or their (a)(i) × 1.5

2

kilowatt-hour accept kWh or a substitution 2100 × 5400 scores 1 mark 2100 × 5400 incorrectly calculated with answer in joules scores 2 marks an answer of 11 340 000 scores 2 marks an answer of 11 340 000 J scores 3 marks

1

(iii) most (input) energy is usefully transformed accept does not waste a lot of energy accept most of the output / energy is useful do not accept it does not waste energy

1

(b) the room is losing energy / heat 1

at the same rate as the heater supplies it this mark only scores if the first is scored do not accept heater reaches same temperature as room / surroundings rate of heat gain = rate of heat loss scores both marks

1 [7]

M14. (a) (matt) black is a good emitter of infrared / radiation

accept heat for infrared / radiation ignore reference to good absorber attracts heat negates this marking point

1

to give maximum (rate of) energy transfer (to surroundings) accept temperature (of coolant) falls fast(er) accept black emits more radiation for 1 mark black emits most radiation / black is the best emitter of radiation for 2 marks

1

of 72

(b) the fins increase the surface area accept heat for energy

1

so increasing the (rate of) energy transfer or so more fins greater (rate of) energy transfer

1

(c) 114 000 allow 1 mark for correct temperature change, ie 15 (°C) or allow 2 marks for correct substitution, ie 2 × 3 800 × 15 answers of 851 200 or 737 200 gain 2 marks or substitution 2 × 3800 × 112 or 2 × 3800 × 97 gains 1 mark an answer of 114 kJ gains 3 marks

3

(d) increases the efficiency 1

less (input) energy is wasted accept some of the energy that would have been wasted is (usefully) used

or

more (input) energy is usefully used accept heat for energy

1 [9]

M15. (a) (i) The volume of boiling water. 1

(ii) any one from:

• (more) precise do not accept better (reading)

• accurate

• reliable do not accept thermometer is unreliable

• removes human / reading error accept easier to read accept take temperature more frequently

1

of 72

(b) B

marks are for the explanation

temperature falls faster this mark point cannot score if A chosen

1

because black is a better / good emitter ignore reference to better absorber accept for both marks an answer in terms of why A is the white can

1

(c) (i) faster than 1

(ii) darker / black surfaces absorb heat faster accept black is a better / good absorber dark surfaces attract heat negates this mark

1

(iii) air is a bad / poor conductor or air is a good insulator

accept air is an insulator 1

[7]

M16. (a) (i) silvered surfaces

more than the correct number of ticks in a row negates the mark

radiation 2

plastic cap

conduction, convection (both required)


vacuum

silvered surfaces (1)

plastic cap (1)

of 72

(ii) any mention of air or any other substance in a vacuum scores zero

because there are no particles in a vacuum accept atoms / molecules for particles accept vacuum is empty space accept there is nothing in a vacuum accept there is no air / gas in the vacuum

conduction and convection need particles / medium

need reference to both conduction and convection accept correct descriptions

2

(b) (i) less heat lost (to air above the heater) do not accept no heat lost

light shiny surfaces are poor emitters (of radiation) accept radiators for emitters references to reflection are neutral

or dull, matt surfaces are good emitters (of radiation)

do not credit answers which infer reflection from the underside of the hood ignore correct reference to absorption

2

(ii) correct diagram drawn with one output arrow narrower than the other

ignore input

arrows correctly labelled with energy form eg

flow charts score zero

2

(iii) energy cannot be destroyed accept (principle of) conservation of energy do not accept because energy cannot be lost without clarification

1 [9]

M17. (a) (i) conduction 1

of 72

(ii) atoms gain (kinetic) energy accept particles / molecules for atoms do not accept electrons for atoms

or atoms vibrate with a bigger amplitude

accept vibrate faster / more do not accept start to vibrate

or atoms collide with neighbouring atoms

1

transferring energy to (neighbouring / other) atoms do not accept heat for energy

or making these other atoms vibrate with a bigger amplitude

accept faster / more for bigger amplitude mention of (free) electrons moving and passing on energy negates this mark

1

(b) (i) 5 (°C) to 25 (°C) either order

1

(ii) a correct example of doubling temperature difference doubling heat transfer

eg going from 5 to 10 (°C) difference doubles heat transfer from 30 to 60 (J/s) accept for heat transfer number of joules / it allow 1 mark for correctly reading 1 set of data eg at 5 °C the heat transfer is 30 or for every 5°C increase in temperature difference heat transfer increases by 30 (J/s) no credit for stating they are directly proportional

2

(iii) 1800 allow 1 mark for obtaining heat transfer value = 120

2

(c) payback time calculated as 33 years calculations must be correct to score the first mark point explanations must relate to it not being cost effective

1

of 72

this is greater than lifetime of windows or total savings (over 30 years) = £4800 (1)

this is less than cost of windows (1) or

this is more than the yearly savings (1) 1

[10]

M18. accept atoms / particles for ions throughout

(a metal has) free electrons accept mobile for free

1

(kinetic) energy of (free) electrons increases accept energy of ions increases accept ions vibrate with a bigger amplitude accept ions vibrate more do not accept electrons vibrate more

1

(free) electrons move faster 1

or

electrons move through metal accept electrons collide with other electrons / ions

(so) electrons transfer energy to other electrons / ions accept ions transfer energy to neighbouring ions

1 [4]

M19. (a) (i) correct data point identified (4, 0.96) 1

(ii) a decrease in 1

= 176 (1)

of 72

(b) (i) no / less atmospheric pollution accept specific examples eg no CO

2 / greenhouse gases produced

accept no harmful gases / fumes accept reduced pollution from transportation (of coal) accept does not contribute to global warming it / they refers to solar cells do not accept no / less pollution does not harm the environment is insufficient it is a renewable energy source is insufficient

1

(ii) 8

2

(iii) increase 1

(iv) these marks can score even if (b)(iii) is wrong

less / no electricity generated accept energy for electricity accept reduced power / voltage output

1

(because) lower light intensity (hitting solar panel / cell) or so decreases money paid / gained (from selling electricity)

allow less light / sun (hitting solar panel / cell) 1

[8]

M20. (a) (i) radiation

ignore thermal / infrared 1

(ii) black is a better / good absorber (of heat / radiation) ignore reference to black being a good emitter black absorbs heat is insufficient do not accept black attracts / absorbs the Sun do not accept black attracts heat

1

allow 1 mark for showing correct method ie provided that no subsequent step is shown

of 72

(so) temperature rises faster must be an indication of heating up quicker

or white is a worse / poor absorber (of heat / radiation) (1)

accept white is a better / good reflector (of heat / radiation)

(so if white faces) temperature would rise slower (1) ignore any reference to light

1

(b) (i) 1.2 (hours) or 1 hour 12 minutes

no tolerance 1

(ii) increases (rapidly at first then increases at a slower rate) do not accept increases at a steady rate

1

(c) (i) any two from:

• (fill with) same mass / volume / amount of water

• same level of (sun)light / sunshine accept same heat / light source accept same place

• outside for the same (length of) time

• outside at same time (of day / year)

• initial water temperature

• the side of the bag facing the Sun do not accept any factors to do with the construction of plastic bags eg thickness

2

(ii) curved line drawn above given line both lines must start from the same point ignore if continues beyond one hour or levels off after 1 hour do not accept a straight line

1 [8]

M21. (a) (i) convection 1

(ii) conduction 1

(b) (i) 2 1

of 72

black is the best absorber (of thermal energy / heat) accept black is the best emitter (of thermal energy / heat) note that a comparative is needed (eg better or best)

1

(ii) the colour of the metal plates 1

(iii) any one from:

• more precise / accurate / reliable do not accept better reading do not accept thermometer is unreliable

• can measure continuously

• take many readings in a small time

• removes (human) reading error accept easier to read

• can compare / draw graphs automatically

• records data automatically 1

(c) (i) radiation accept radiates accept infra red (IR) waves do not accept heat waves

1

(ii) to reflect (heat away from the fire fighter) accept it reflects accept it is a poor absorber (of thermal radiation / heat) do not accept deflect / bounce for reflect

1

(d) N

the mark is for the reason which does not score if M is chosen

transfers / absorbs less heat or gives smallest increase in temperature

accept will keep fire fighters cooler accept N is cooler (after 15 minutes) an answer N goes up to 52°C and M goes up to 100°C is insufficient

1 [9]

of 72

M22. (a) to reflect (the infrared)

accept (shiny surfaces) are good reflectors ignore reference to incorrect type of wave

1

(b) black 1

best absorber (of infrared) answer should be comparative black absorbs (infrared) is insufficient accept good absorber (of infrared) ignore reference to emitter ignore attracts heat ignore reference to conduction

1

(c) to reduce energy loss accept to stop energy loss accept heat for energy accept to stop / reduce convection

or so temperature of water increases faster

accept to heat water faster accept cooks food faster

or reduces loss of water (by evaporation)

1

(d) 672 000 allow 1 mark for correct substitution, ie 2 × 4200 × 80 provided no subsequent step shown

2 [6]

M23. (a) (i) vacuum

do not allow stopper 1

(ii) (absence of particles) means no (transfer of energy between) particles for conduction

accept particles or atoms or molecules or electrons 1

of 72

no movement of molecules for (transfer of energy by) convection accept particles/atoms/electrons if answer to (a)(i) is correct: then in (a)(ii) have stated ‘conduction and convection both need a medium/particles/materials’ = 2 marks (If medium is specified, it must be correct, conduction can be solid, liquid or gas, convection must be liquid or gas) if answer to (a)(i) is incorrect then in (a)(ii) have stated ‘conduction and convection both need a medium...’= 1 mark, unless further qualified by stating about absence of particles, in which case get a second mark.

1

(b) (i) silvered surface accept silver surface

1

(ii) silvered is a bad emitter/radiator 1

surface reflects heat/energy/radiation (at inner and outer surface) or is a bad absorber (of energy)

accept bounces off 1

[6]

M24. (a) B

no mark for B - marks are for the explanation first two mark points can score even if A is chosen

draught increases (the rate of) evaporation accept more evaporation happens accept draught removes (evaporated) particles faster do not accept answers in terms of particles gaining energy from the fan / draught

1

evaporation has a cooling effect accept (average) kinetic energy of (remaining) particles decreases

1

so temperature will fall faster / further 1

(b) larger surface area 1

of 72

increasing the (rate of) evaporation accept more / faster evaporation accept easier for particles to evaporate

or

for water to evaporate from accept more particles can evaporate accept water / particles which have evaporated are trapped (in the bag) answers in terms of exposure to the Sun are insufficient

1 [5]

M25. (a) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking guidance.

0 marks No relevant content.

Level 1(1-2 marks) There is a basic explanation of one feature or a simple statement relating reduction in energy transfer to one feature.

Level 2(3-4 marks) There is a clear explanation of one feature or a simple statement relating reduction in energy transfer to two features.

Level 3(5-6 marks) There is a detailed explanation of at least two features or a simple statement relating reduction in energy transfer to all four features.

of 72

Examples of the points made in response

extra information accept throughout: heat for energy loss for transfer

plastic cap:

• plastic is a poor conductor accept insulator for poor conductor

• stops convection currents forming at the top of the flask so stopping energy transfer by convection

• molecules / particles evaporating from the (hot) liquid cannot move into the (surrounding) air so stops energy transfer by evaporation

• plastic cap reduces / stops energy transfer by conduction / convection / evaporation

glass container:

• glass is a poor conductor so reducing energy transfer by conduction

• glass reduces / stops energy transfer by conduction

vacuum:

• both conduction and convection require a medium / particles

• so stops energy transfer between the two walls by conduction and convection

• vacuum stops energy transfer by conduction / convection

silvered surfaces:

• silvered surfaces reflect infrared radiation accept heat for infrared

• silvered surfaces are poor emitters of infrared radiation

• infrared radiation (partly) reflected back (towards hot liquid)

• silvered surfaces reduce / stop energy transfer by radiation 6

(b) (the ears have a) small surface area ears are small is insufficient

1

so reducing energy radiated / transferred (from the fox) accept heat lost for energy radiated do not accept stops heat loss

1 [8]

of 72

M26. (a) (i) £150

gets 2

Else 1000 – (250 + 350 + 100 + 150) or 1000 – 850 gets 1

2

(ii) (Named) floor covering OR Insulation under floor

for 1 mark 1

(b) (i) Draught proof doors or fibre glass in loft or in cavity For draught proofing

gains 1 mark

Very low cost/easy to install Repays for itself quickly/cost recuperated quickly Reasonable energy saving

any 2 for 1 mark each

For loft insulation

Second lowest installation cost/easy to install Reasonable large energy savings for this cost Reasonable payback time

gains 1 mark

For foam filled cavity Biggest energy/cash saving Cost effective

any 2 for 1 mark each 3

(ii) Double glazing

gains 1 mark

Costs most Saves least energy Least cost effective

any 2 for 1 mark each 3

[9]

of 72

energy transfers (particle theory, conduction, convection...

Documents