MS.RAJA ELGADY/HEAT PAPER 3...MS.RAJA ELGADY/HEAT PAPER 3 4- (a) Some water is poured onto a plastic...

MS.RAJA ELGADY/HEAT PAPER 31- Fig. 11.1 is a schematic diagram of an electronic circuit controlling a lamp.

temperaturesensor

ForExaminer’s

Use

MS.RAJA ELGADY/HEAT PAPER 31- Fig. 11.1 is a schematic diagram of an electronic circuit controlling a lamp.

temperature sensor

lightsensor

F

Fig. 11.1 (a) State the names

of the logic gates A and B.

A ........................................................ B ........................................................[2]

relay lamp

B

A

MS.RAJA ELGADY/HEAT PAPER 3(b) The output of the temperature sensor is high (logic 1) when it detects raised

temperature.The output of the light sensor is high (logic 1) when it detects

raised light levels. State the outputs of A and B when the

surroundings are

(i) dark and cold, output of A = ....................................

output of B = .................................... [1]

(ii) dark and warm, output of A = ....................................

output of B = .................................... [1]

(iii) bright and warm. output of A = ....................................

output of B = .................................... [1]

(c) (i) Suggest why B is connected to a relay, rather than directly to the lamp.

............................................................................................................................[1]

(ii) The relay switches on when its input is high. In which of the threecombinations in

(b) will the lamp light up?

............................................................................................................................[1]

(iii) Suggest a practical use for this circuit.

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

[1]

[Total:

8]

MS.RAJA ELGADY/HEAT PAPER 3

MS.RAJA ELGADY/HEAT PAPER 32- One side of a copper sheet is highly polished and the other side is painted mattblack.

MS.RAJA ELGADY/HEAT PAPER 32- One side of a copper sheet is highly polished and the other side is painted mattblack.

The copper sheet is very hot and placed in a vertical position, as shown as in Fig. 5.1.

ForExaminer’s

Use

matt black side

copper sheet

polished side

left hand right hand

Fig. 5.1

A student places her hands at equal distances from the sheet, as shown in Fig. 5.1.

(a) Explain

(i) why her hands are not heated by convection,

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

............................................................................................................................. [1]

(ii) why her hands are not heated by conduction.

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

............................................................................................................................ . [1]

(b) State and explain which hand gets hotter.

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

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

.................................................................................................................... ................. [2]

(c) It is suggested that one side of the copper sheet cools to a lower temperature than theother side.

Explain why this does not happen.

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

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

............................................................................................................................. ........ [2]

[Total: 6]

MS.RAJA ELGADY/HEAT PAPER 33- (a) Equal volumes of a gas held at constant pressure, a liquid and a solid undergo the same

temperature rise.

(i) State which of the three, solid, liquid or gas,

1. expands the most, ..............................

2. expands the least. ..............................

(ii) Explain why the pressure of the gas must be kept constant for this comparison.

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

...................................................................................................................................... .[2]

(b) Fig. 5.1 shows an alcohol thermometer.

–10 0 10 20 30 40 50 60 70 °C

Fig. 5.1

(i) State two properties of alcohol which make it suitable for use in a thermometer.

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

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

2. ............................................................................................................................. ...........

............................................................................................ ...........................................[2]

(ii) State two changes to the design of this thermometer which would make it moresensitive.

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

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

2. ............................................................................................................................. ...........

............................................................................................ ...........................................[2]

(c) Explain why it is an advantage for the glass surrounding the alcohol in the bulb of thethermometer to be very thin.

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

.......................................................................................... .....................................................[1]

[Total: 7]

MS.RAJA ELGADY/HEAT PAPER 34- (a) Some water is poured onto a plastic table-top, forming a puddle. The same volume of

water is poured into a plastic dish, which is placed alongside the puddle.This is illustratedin Fig. 7.1.

ForExaminer’s

Use

water inpuddle

water indish

Fig. 7.1

Both lots of water begin to evaporate.

(i) In terms of the behaviour of molecules, describe what happens during the processof evaporation.

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

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

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

............................................................................................................................ [2]

(ii) Explain why the puddle dries out more rapidly than the water in the dish.

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

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

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

............................................................................................................................ [2]

(iii) State two changes that would make both lots of water evaporate more rapidly.

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

2. ......................................................................................................................... [2]

MS.RAJA ELGADY/HEAT PAPER 3(b) In a place where refrigeration is not possible, a person attempts to keep a bottle of milk

cool by using the procedure illustrated in Fig. 7.2.For

Examiner’sUse

damp cloth

bottle

milk

water bowl

Fig. 7.2

Explain in terms of molecules why this procedure would be successful.

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

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

............................................................................................................................. ....... [3]

[Total: 9]

MS.RAJA ELGADY/HEAT PAPER 39 (a) State what is meant by specific heat capacity.

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

............................................................................................................................. ....... [2]

(b) Water has a very high specific heat capacity.

Suggest why this might be a disadvantage when using water for cooking.

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

................................................................................................. ................................... [1]

(c) Fig. 9.1 illustrates an experiment to measure the specific heat capacity of some metal.

ForExaminer’s

Use

stirrerthermometer

lid

boiling water

metal

thread

water

cup

insulation

heater

Fig. 9.1

The piece of metal is heated in boiling water until it has reached the temperature ofthe water. It is then transferred rapidly to some water in a well-insulated cup. A verysensitive thermometer is used to measure the initial and final temperatures of the waterin the cup.

specific heat capacity of water = 4200J/ (kg K)

The readings from the experiment are as follows.

mass of metal = 0.050kgmass of water in cup = 0.200kginitial temperature of water in cup = 21.1°Cfinal temperature of water in cup = 22.9°C

(i) Calculate the temperature rise of the water in the cup and the temperature fall ofthe piece of metal.

temperature rise of water = ......................................................

temperature fall of metal = ......................................................[1]

MS.RAJA ELGADY/HEAT PAPER 3

MS.RAJA ELGADY/HEAT PAPER 3(ii) Calculate the thermal energy gained by the water in the cup. State the equation that

you use.

thermal energy gained = ................................................ [3]

(iii) Assume that only the water gained thermal energy from the piece of metal.

Making use of your answers to (c)(i) and (c)(ii), calculate the value of the specific heatcapacity of the metal. Give your answer to 3 significant figures.

specific heat capacity = ................................................ [2]

(iv) Suggest one reason why the experiment might not have given a correct value for thespecific heat capacity of the metal.

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

............................................................................................................................ [1] [Total: 10]

6- (a) Smoke particles are introduced into a glass box containing air. Light shines into the box sothat, when observed through a microscope, the smoke particles can be seen as bright pointsof light.

Describe the motion of the smoke particles and account for this motion in terms of the airmolecules.

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

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

MS.RAJA ELGADY/HEAT PAPER 3............................................................................................................................. ......................

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

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

............................................................................................................................. ..................[4]

(b) Fig. 5.1 shows a quantity of gas in a cylinder sealed by a piston that is free to move.

gas

cylinder piston

Fig. 5.1

(i) The temperature of the gas is increased.

State what happens, if anything,

1. to the piston,

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

2. to the pressure of the gas.

............................................................................................................................. ..............[2]

(ii) The piston is now fixed in place and the temperature of the gas is increased further.

Explain, in terms of the behaviour of molecules, what happens to the pressure of the gas.

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

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

................................................................................................................... ....................[2] [Total: 8]

7- (a) State what is meant by the specific heat capacity of a substance.

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

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

MS.RAJA ELGADY/HEAT PAPER 3............................................................................................................................. ................. [2]

(b) A student carries out an experiment to find the specific heat capacity of aluminium. He usesan electric heater and a thermometer, inserted into separate holes in an aluminium block.

The following data are obtained.

mass of aluminium block = 2.0kgpower of heating element = 420Wtime of heating = 95sinitial temperature of block = 19.5°Cfinal temperature of block = 40.5°C

Calculate the value of the specific heat capacity of aluminium given by this experiment.

specific heat capacity = ............................................... [4]

(c) In the experiment in (b), no attempt is made to prevent loss of thermal energy from thesurfaces of the block.

Suggest two actions the student could take to reduce the loss of thermal energy from thesurfaces of the block.

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

2. ............................................................................................................................. .................[2]

[Total: 8]

77MS.RAJA ELGADY/HEAT PAPER 38-FIG 6.1 SHOW

P

gas

Fig. 6.1

(a) Describe the motion of the molecules of the gas.

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

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

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

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

.............................................................................................................................................. [3]

(b) The piston is now slowly pushed down to decrease the volume of the gas. The temperature ofthe gas does not change.

(i) State and explain, in terms of molecules, what happens to the pressure of the gas.

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

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

............................................................................................................................. ......... [2]

(ii) Before pushing the piston down, the pressure of the gas was 1.0 × 105 Pa. Pushing thepiston down reduces the volume of the gas from 500cm3 to 240cm3.

Calculate the final pressure of the gas.

pressure = ................................................ [2]

[Total: 7]

88MS.RAJA ELGADY/HEAT PAPER 39- (a) An object of mass m and specific heat capacity c is supplied with a quantity of thermal

energy Q. The temperature of the object increases by Δθ.

Write down an expression for c in terms of Q, m and Δθ.

c = ............................................................[1]

(b) Fig. 4.1 shows the heating system of a hot water shower.

power supply

cold water in hot water out

heating element

Fig. 4.1

Cold water at 15°C flows in at the rate of 0.0036m3 /minute. Hot water flows out at the samerate.

(i) Calculate the mass of water that passes the heating element in one minute. The densityof water is 1000 kg /m3.

mass = ...........................................................[2]

(ii) The power of the heating element is 8.5kW.

Calculate the temperature of the hot water that flows out. The specific heat capacity ofwater is 4200J/(kg°C).

temperature = ...........................................................[4]

[Total: 7]

99MS.RAJA ELGADY/HEAT PAPER 310- A small cylinder of compressed helium gas is used to inflate balloons for a celebration.

(a) (i) In the box below, sketch a diagram to represent the arrangement of heliummolecules in a balloon.

[2]

(ii) State and explain how the size of the attractive forces acting between themolecules of a gas compares with the size of the attractive forces between themolecules of a solid.

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

.........

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

.........

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

.....[2]

(b) The helium in the cylinder has a volume of 6.0 ×10–3 m3 (0.0060m3) and is at a pressureof

2.75 ×106 Pa.

(i) The pressure of helium in each balloon is 1.1 ×105 Pa.The volume of helium in aninflated balloon is 3.0 ×10–3 (0.0030m3). The temperature of the helium does notchange.

Calculate the number of balloons that were inflated.

number of balloons = ................................................[3]

(ii) Later, the temperature increases and some of the balloons burst.

Suggest and explain why this happens.

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

.........

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1010MS.RAJA ELGADY/HEAT PAPER 3

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

............................................................................................................................. ..........[2] [Total: 9]

11- Fig. 4.1 shows a cross-section of a double-walled glass vacuum flask, containing a hotliquid.

The surfaces of the two glass walls of the flask have shiny silvered coatings.

ForExaminer’s

Use

silveredsurfaces

vacuum

hot liquid

Fig. 4.1

(a) Explain

(i) why the rate of loss of thermal energy through the walls of the flask by conductionis very low,

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

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

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

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

(ii) why the rate of loss of thermal energy through the walls of the flask by radiation isvery low.

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

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

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

............................................................................................................................. .....[3]



(b) Suggest, with reasons, what must be added to the flask shown in Fig. 4.1 in order tokeep the liquid hot.

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

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

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

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

............................................................................................ .......................................... [3] [Total: 6]

relay lamp

B

A


light sensor

F

12-fig. 11.1 (a) State the names of

the logic gates A and B.

A ........................................................ B ........................................................ [2]

(b) The output of the temperature sensor is high (logic 1) when it detects raisedtemperature.

The output of the light sensor is high (logic 1) when it detects raised

light levels. State the outputs of A and B when the surroundings are

(i) dark and cold, output of A = ....................................

output of B = .................................... [1]

(ii) dark and warm, output of A = ....................................

output of B = .................................... [1]

(iii) bright and warm. output of A = ....................................

output of B = .................................... [1]

(c) (i) Suggest why B is connected to a relay, rather than directly to the lamp.

............................................................................................................................ [1]


13- Fig. 5.1 shows a thin plastic cup containing hot coffee, which an IGCSE Physics student getsfrom a machine.


13- Fig. 5.1 shows a thin plastic cup containing hot coffee, which an IGCSE Physics student getsfrom a machine.

Fig. 5.2 shows how another student, who finds an empty second cup, has placed his identicalcup of coffee inside this second cup.

ForExaminer’s

Use

thick rim

coffeecoffee

thin cup

single cup double cup

Fig. 5.1 Fig. 5.2

(a) Suggest and explain a difference that the students will feel when holding the cups.

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

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

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

............................................................................. ........................................................ [2]


(b) The students discuss this experience with their teacher, who makes hot drinks thesubject of an experiment.

The same volume of hot water at the same temperature is placed in the single cup andin the double cup.

The temperature of the water in each cup is recorded for 10 minutes.

Fig. 5.3 shows the cooling curve for the water in the single cup.

ForExaminer’s

Use

single cup80

70temperature

/ °C 60

5040

0 2 4 6 8 10time /minutes


Fig.5.3

On Fig. 5.3, sketch and label a possible cooling curve for the water in the double cup.[2]

(c) Explain why a cup of coffee cools more slowly when a lid is placed over the cup.

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

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

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

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

............................................................................................................................. ........ [2] [Total: 6]5 (a) Suggest

(i) an example of a change of state resulting from the removal of thermal energy from aquantity of material,

............................................................................................................................. . [1]

(ii) the effect of this change of state on the temperature of the material.

............................................................................................................................. [1]

(b) Define the thermal capacity of a body.

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

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

............................................................................................................................. ........ [2]

(c) A polystyrene cup holds 250 g of water at 20 °C. In order to cool the water to make a colddrink, small pieces of ice at 0 °C are added until the water reaches 0 °C and no unmeltedice is present.

[specific heat capacity of water = 4.2J / (g °C), specific latent heat of fusion of ice =330J /g]

Assume no thermal energy is lost or gained by the cup.

(i) Calculate the thermal energy lost by the water in cooling to 0°C.

thermal energy lost = ................................................. [2]


(ii) State the thermal energy gained by the ice in melting.

thermal energy gained = ................................................. [1]

(iii) Calculate the mass of ice added.

mass of ice = ................................................. [2] [Total: 9]

14- Fig. 5.1 shows a model cable-car system. It is driven by an electric motor coupled to a gearsystem.

gears

2.0 m electricmotor

smoothpulley

modelcable-car

Fig. 5.1

The model cable-car has a mass of 5.0kg and is lifted from the bottom pulley to the top pulley in40s. It stops automatically at the top.

(a) Calculate

(i) the average speed of the cable-car,

average speed = .......................................................... [2]

(ii) the gravitational potential energy gained by the cable-car,


gravitational potential energy gained = .......................................................... [2]


(iii) the useful output power of the driving mechanism.

power = ......................................................... [2]

(b) How would the electrical power input to the motor compare with your answer to (a)(iii)?

............................................................................................................................. ................ [1][Total: 7]

15- Three wires and a meter are used to construct a thermocouple for measuring the surfacetemperature of a pipe carrying hot liquid, as shown in Fig. 7.1.

ForExaminer’s

Use

meter

wire 1 wire 2

cold junction

hot junctionwire 3

hot liquid in pipe

Fig. 7.1

(a) Copper wire and constantan wire are used in the construction of the thermocouple.

State which metal might be used for

wire 1 ......................................................

wire 2 ......................................................

wire 3 ......................................................[1]

(b) State what type of meter is used.

.................................................................................................................................... [1]

(c) State one particular advantage of thermocouples for measuring temperature.

............................................................................................................................. ....... [1]

[Total: 3]


16-

(a) State what is meant by specific heat capacity.

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

................................................................................................................. ................... [2]

(b) Water has a very high specific heat capacity.

Suggest why this might be a disadvantage when using water for cooking.

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

............................................................................................................................. ....... [1]

(c) Fig. 9.1 illustrates an experiment to measure the specific heat capacity of some metal.

ForExaminer’s

Use

stirrerthermometer

lid

boiling water

metal

thread

water

cup

insulation

heater

Fig. 9.1

The piece of metal is heated in boiling water until it has reached the temperature ofthe water. It is then transferred rapidly to some water in a well-insulated cup. A verysensitive thermometer is used to measure the initial and final temperatures of the waterin the cup.

specific heat capacity of water = 4200J/ (kg K)

The readings from the experiment are as follows.

mass of metal = 0.050kgmass of water in cup = 0.200kginitial temperature of water in cup = 21.1°Cfinal temperature of water in cup = 22.9°C

(i) Calculate the temperature rise of the water in the cup and the temperature fall ofthe piece of metal.

temperature rise of water = ......................................................

temperature fall of metal = ......................................................[1]



(ii) Calculate the thermal energy gained by the water in the cup. State the equationthat you use.

thermal energy gained = ................................................ [3]

(iii) Assume that only the water gained thermal energy from the piece of metal.

Making use of your answers to (c)(i) and (c)(ii), calculate the value of the specificheat capacity of the metal. Give your answer to 3 significant figures.

specific heat capacity = ................................................ [2]

(iv) Suggest one reason why the experiment might not have given a correct value forthe specific heat capacity of the metal.

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

.................................................................................................................... ........ [1] [Total: 10]

18- Fig. 5.1 shows apparatus that could be used to determine the specific latent heat of fusion ofice.

ForExaminer’s

Use

finely crushed ice

40W electric heater glass funnel

stand with clamps to holdfunnel and heater


Fig. 5.1

(a) In order to obtain as accurate a result as possible, state why it is necessary to

(i) wait until water is dripping into the beaker at a constant rate before takingreadings,

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

............................................................................................................................ [1]

(ii) use finely crushed ice rather than large pieces.

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

............................................................................................................................ [1]

(b) The power of the heater and the time for which water is collected are known. Write downall the other readings that are needed to obtain a value for the specific latent heat offusion of ice.

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

..................................................................................................... ............................... [2]



(c) Using a 40W heater, 16.3g of ice is melted in 2.0 minutes. The heater is then switched off. In afurther 2.0 minutes, 2.1g of ice is melted.

Calculate the value of the specific latent heat of fusion of ice from these results.

specific latent heat of fusion of ice = ................................................ [4] [Total: 8]

19- The whole of a sealed, empty, dusty room


is kept at a constant temperature of 15°C. Light shines into the room through a small outside window.

An observer points a TV camera with a magnifying lens into the room through a second smallwindow, set in an inside wall at right angles to the outside wall.

Dust particles in the room show up on the TV monitor screen as tiny specks of light.

(a) In the space below draw a diagram to show the motion of one of the specks of light over a shortperiod of time.

[1]

(b) After a period of one hour the specks are still observed, showing that the dust particles have notfallen to the floor.

Explain why the dust particles have not fallen to the floor. You may draw a labelled diagramto help your explanation.

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

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

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

............................................................................................ ........................................ [2]

(c) On another day, the temperature of the room is only 5°C. All other conditions are the sameand the specks of light are again observed.

Suggest any differences that you would expect in the movement of the specks when thetemperature is 5°C, compared to before.

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

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

.................................................................................................................... ................ [1] [Total: 4]


20-

(a)

(b)

State two differences between evaporation of water and boiling of water.

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

2. ...................................................................................................................... ............[2]

The specific latent heat of vaporisation of water is 2260kJ /kg.Explain why this energy is needed to boil water and why the temperature of the waterdoes not change during the boiling.

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

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

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

................................................................................... ...................................................[3]

(c) A laboratory determination of the specific latent heat of vaporisation of water uses a120 W heater to keep water boiling at its boiling point. Water is turned into steam at therate of 0.050 g /s.Calculate the value of the specific latent heat of vaporisation obtained from thisexperiment. Show your working.

ForExaminer’s

Use

specific latent heat of vaporisation = ........................[3]


21- (a) Fig. 5.1 shows a tank used for evaporating salt solution to producecrystals.

evaporating tank

ForExaminer’s

Use

salt solutionsteam in

steam out

Fig. 5.1

Suggest two ways of increasing the rate of evaporation of the water from the solution.Changes may be made to the apparatus, but the rate of steam supply must stay constant.You may assume the temperature of the salt solution remains constant.

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

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

2. ............................................................................................................................. .........

......................................................................................................................................[2]

(b) A manufacturer of liquid-in-glass thermometers changes the design in order to meetnew requirements.

Describe the changes that could be made to

(i) give the thermometer a greater range,

............................................................................................................................. .[1]

(ii) make the thermometer more sensitive.

............................................................................................................................. .[1]

(c) A toilet flush is operated by the compression of air. The air inside the flush has apressure of 1.0 × 105 Pa and a volume of 150 cm3. When the flush is operated thevolume is reduced to 50 cm3. The temperature of the air remains constant during thisprocess.Calculate the new pressure of the air inside the flush.

pressure = .......................[2]


22- Fig. 4.1 shows apparatus that could be used to measure the specific latent heat ofice.

60W heater

ForExaminer’s

Use

power supply

melting ice at 0 °C

beaker

Fig. 4.1

(a) Describe how you would use the apparatus. You may assume that ice at 0 °C and astopwatch are available. State all the readings that would be needed at each stage.

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

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

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

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

............................................................................................................................. ........ [4]

(b) In an experiment, 120 g of ice at 0 °C is to be melted. The specific latent heat of ice is340 J/g. Assume that all the energy from the heater will be used to melt the ice.

Calculate the expected time for which the 60 W heater is switched on.

expected time = …………………… [2]

(c) When the experiment is carried out, the ice melts in slightly less time than the expectedtime.

(i) State one reason why this happens.

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

............................................................................................................................. . [1]

(ii) Suggest one modification to the experiment that would reduce the differencebetween the experimental time and the expected time.

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



60W heater

ForExaminer’s

Use

power supply


beaker

Fig. 4.1


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

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

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

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

............................................................................................................................. ........ [4]






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

............................................................................................................................. . [1]


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



60W heater

ForExaminer’s

Use

power supply


beaker

Fig. 4.1


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

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

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

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

............................................................................................................................. ........ [4]






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

............................................................................................................................. . [1]


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


............................................................................................. ................................. [1]


23- (a) Fig. 5.1 shows a copper rod AB being heated at oneend.

copper rod

ForExaminer’s

Use

B A

Bunsenburner

Fig. 5.1

(i) Name the process by which heat moves from A to B.

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

(ii) By reference to the behaviour of the particles of copper along AB, state how thisprocess happens.

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

.......................................................................................................... ........................[3]

(b) Give an account of an experiment that is designed to show which of four surfaces willabsorb most heat radiation.The four surfaces are all the same metal, but one is a polished black surface, one is apolished silver surface, one is a dull black surface and the fourth one is painted white.Give your answer under the headings below.

labelled diagram of the apparatus

readings to be taken

one precaution to try to achieve a fair comparison between the various surfaces

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

............................................................................................................................. .........[3]


24- Fig. 4.1 shows some of the apparatus that a student uses to determine the specific heat capacityof aluminium.

connections to electric circuit

electric heater

insulating lid

thermometer

aluminium block

insulating container

Fig. 4.1

(a) State the measurements the student needs to make, including those from the electric circuit.For each quantity measured, state a symbol.

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

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

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

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

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

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

............................................................................................................................. ..................[4]


(b) Use your symbols from (a) to complete the formula used to determine the specific heatcapacity c.

specific heat capacity c =

.................................................................................. .[2]

(c) Another student performs the experiment without using insulation. He obtains a higher valuefor c.

Explain why this student’s measurements lead to this higher value.

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

.............................................................................................................................................................. [1] [Total: 7]

25- (a) The following are three statements aboutboiling.

• A liquid boils at a fixed temperature.

• During boiling, vapour can form at any point within the liquid.

• Without a supply of thermal energy, boiling stops.

Complete the following equivalent statements about evaporation.

• A liquid evaporates at ........................................................................................................

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

• During evaporation .............................................................................................................

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

• Without a supply of thermal energy, evaporation ............................................................ .[3]

(b) A pan containing water boiling at 100°C is standing on an electrically heated hot-plate. In20 minutes, 0.075kg of water is lost as steam. The specific latent heat of vaporisation ofwater is 2.25 × 106 J /kg.

(i) Calculate the energy used in converting 0.075kg of boiling water to steam.

energy = ............................................... [2]


(ii) The hot-plate operates at 240V, 0.65A.

Calculate the energy supplied to the hot-plate in 20 minutes.

energy = ............................................... [2]

(iii) Suggest why the answers to (b)(i) and (b)(ii) are not the same.

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

.................................................................................................. .................................... [1]

[Total: 8]


26- (a) On a hot day, sweat forms on the surface of a person’s body and the sweatevaporates.

Explain, in terms of the behaviour of molecules,

(i) the process of evaporation,

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

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

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

(ii) how this process helps the body to cool down.

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

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

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

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

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

............................................................................................................................ ......[3]

(b) The temperature of a person of mass 60kg falls from 37.2 °C to 36.7°C.

(i) Calculate the thermal energy lost from the body.The average specific heat capacityof the body is 4000J/ (kg°C).

thermal energy lost = .................................................. [2]

ForExaminer’s

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27-

(a) A certain volume of water at room temperature and the same volume of ice in a freezerare each heated through the same temperature rise.

Which of them will have the greater expansion, and why?

Which? .............................................................................................................................

Why? .......................................................................................................................... [1]

(b) For strength, concrete pillars are usually reinforced with metal rods, which are embeddedin the concrete before it sets.

The list below shows how much a length of 1m of each material expands when thetemperature rises by 1°C.

(ii) The cooling of the body was entirely due to the evaporation of sweat.

Calculate the mass of sweat which evaporated. The specific latent heat ofvaporisation of sweat is 2.4×106 J /kg.

mass = .................................................. [2] [Total: 7]

For

Examiner’s

Use

a

l

u

m

i

n

i

u

m


0.03 mm

concrete

0.01 mm steel

0.01mm

Use this information to decide which metal should be used to reinforceconcrete, why it is suitable, and why the other metal is not suitable.

Which metal should be used?

.......................................................................................... W hy is it suitable?

............................................................................................................ W hy is

the other metal unsuitable?

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

............................................................................................................................. ....... [3] [Total: 4]

6


28-Solar panels are positioned on the roof of the house shown in Fig. 6.1. They use thermalenergy from the Sun to provide hot water in an environmentally friendly way.

ForExaminer’s

Use

solarpanels

Fig. 6.1

Cold water flows to the panels at 15°C. During the day, the panels supply 3.8kg of hot waterat 65°C every hour.

(a) Calculate the average energy that the solar panels deliver to the water in one hour.Specific heat capacity of water = 4200J/ (kg °C).

energy = ................................................. [3]

(b) The solar power incident on the roof during this heating period is 170W /m2. The solarpanels have a total area of 8.0m2.

Calculate the solar energy incident on the panels in one hour.

solar energy = ................................................. [2]

(c) Calculate the efficiency of the solar panels, stating the equation you use.

efficiency = ................................................. [2]



(d) Explain why solar energy is called renewable energy.

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

.................................................................................................................... ................. [1]

(e) State one disadvantage of using solar energy.

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

..................................................................................................................................... [1] [Total: 9]

For

Examiner’s

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5 (a) Explain, in terms of molecules, how thermal expansion takes place in a solid and in agas.

solid ............................................................................................................................. ....

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

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

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

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

gas ............................................................................................................................. ......

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

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

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

............................................................................................................................. ....... [4]

(b) Complete Table 5.1 to show the relative expansion of equal volumes of liquids, gasesand solids.

Choose words frommuch less, slightly less, slightly more and much more.[2]

state of matter expansion compared to solids, for thesame temperature rise

liquids

gases

T

A


b

le 5.1 (c) Alcohol is often used in

thermometers.

State one property of alcohol that makes it suitable for use in thermometers.

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

.

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

.

............................................................................................................................. ....... [1] [Total: 7]

ForExaminer’s

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30- Fig. 6.1 shows a glass flask full of water at 10°C and sealed with a bung. A long glass tube passesthrough the bung into the water. The water level in the tube is at X.

bung X

glass flask

water

Fig. 6.1

When the flask is placed in hot water, the water level initially falls a little below X, and thenrises some way above X.

(a) Suggest why

(i) the water level initially falls,

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

............................................................................................................................ . [2]

(ii) the water level then rises,

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

................................................................................. ............................................ [2]

(iii) the rise is greater than the fall.

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

............................................................................................................................. [1]

(b) Suggest a change to the apparatus that would make the fall and rise of the water levelgreater.

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

............................................................................................................................. ........ [1] [Total: 6]


31- Fig. 5.1 shows some apparatus designed to compare the ability of two surfaces to absorbinfra-red radiation.

surfacepainted

dullblack

surfacepainted

shiny white

Fig. 5.1

Bunsen burner

The containers, which are identical, are painted on the outside. One is dull black, the other isshiny white. Both are filled with water, initially at the same temperature.

(a) (i) Describe how you would use the apparatus to compare the abilities of the twosurfaces to absorb infra-red radiation.

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

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

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

............................................................................................................................ [2]

(ii) State the result that you would expect.

............................................................................................................................ [1]

(b) The thermometers used have high sensitivity and linear scales.

(i) State what is meant by high sensitivity.

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

............................................................................................................................ [1]

(ii) Explain why a high sensitivity is important for this experiment.

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

............................................................................................................................ [1]

(iii) State what is meant by a linear scale.

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


............................................................................................................. ............... [1]

[Total: 6]


32- Fig. 4.1 shows a student’s attempt to estimate the specific latent heat of fusion of ice byadding ice at 0°C to water at 20°C. The water is stirred continuously as ice is slowly addeduntil the temperature of the water is 0 °C and all the added ice has melted.

Examiner’sUse

thermometer

ice

water

glass rodstirrer

glass beaker

top-pan balance

Fig. 4.1

(a) Three mass readings are taken. A description of the first reading is given.

Write down descriptions of the other two.

reading 1 the mass of the beaker + stirrer + thermometer

reading 2 .........................................................................................................................

reading 3 ................................................................................................................... [2]

(b) Write down word equations which the student could use to find

(i) the heat lost by the water as it cools from 20°C to 0 °C,

............................................................................................................................ [1]

(ii) the heat gained by the melting ice.

............................................................................................................................ [1]



Examiner’sUse

thermometer

ice

water

glass rodstirrer

glass beaker

top-pan balance

Fig. 4.1




reading 2 .........................................................................................................................

reading 3 ................................................................................................................... [2]



............................................................................................................................ [1]


............................................................................................................................ [1]



Examiner’sUse

thermometer

ice

water

glass rodstirrer

glass beaker

top-pan balance

Fig. 4.1




reading 2 .........................................................................................................................

reading 3 ................................................................................................................... [2]



............................................................................................................................ [1]


............................................................................................................................ [1]

ForExaminer’s

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7 ForExaminer’s

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7MS.RAJA ELGADY/HEAT PAPER 3(c) The student calculates that the water loses 12800J and that the mass of ice melted is

30g.

Calculate a value for the specific latent heat of fusion of ice.

specific latent heat of fusion = ................................................ [2]

(d) Suggest two reasons why this value is only an approximate value.

Reason 1 .........................................................................................................................

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

Reason 2 .........................................................................................................................

............................................................................................................................. ....... [2]

[Total: 8]

ForExaminer’s

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8 ForExaminer’s

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8MS.RAJA ELGADY/HEAT PAPER 333- Fig. 5.1 shows a way of indicating the positions and direction of movement of some

molecules in a gas at one instant. ForExaminer’s

Use

cylinderpiston

ForExaminer’s

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9 ForExaminer’s

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9MS.RAJA ELGADY/HEAT PAPER 3Fig. 5.1

(a) (i) Describe the movement of the molecules.

............................................................................................................................. .[1]

(ii) Explain how the molecules exert a pressure on the container walls.

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

.

............................................................................................................................. .[1]

(b) When the gas in the cylinder is heated, it pushes the piston further out of the cylinder.

State what happens to

(i) the average spacing of the molecules,

............................................................................................................................. .[1]

(ii) the average speed of the molecules.

............................................................................................................................. .[1]

(c) The gas shown in Fig. 5.1 is changed into a liquid and then into a solid by cooling.

Compare the gaseous and solid states in terms of

(i) the movement of the molecules,

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

.

............................................................................................................................. .[1]

(ii) the average separation of the molecules.

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

.

............................................................................................................................. . [1]

ForExaminer’s

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10

ForExaminer’s

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10MS.RAJA ELGADY/HEAT PAPER 335- Fig. 5.1 shows some apparatus which is to be used to compare the emission of infra-red

radiation from four differently painted surfaces.

Examiner’sUse

this sidepainted shiny

white

metal box

this sidepainted dull

white

water inlet

this sidepainted dull

black

this sidepainted shiny

black

Fig. 5.1

Near the centre of each side is an infra-red detector. The four detectors are identical.

A supply of very hot water is available.

(a) Describe how you would use this apparatus to compare the infra-red radiation from thefour surfaces.

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

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

............................................................................................................................. ....... [3]

(b) Suggest which surface will be the best emitter and which will be the worst emitter.

best emitter ...........................................

worst emitter ......................................... [1]

(c) The infra-red detectors are made from thermocouples soldered to blackened metalplates. These are connected to galvanometers.

In the space below, draw a labelled diagram of a thermocouple. [2]

[Total: 6]

ForExaminer’s

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11

ForExaminer’s

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11MS.RAJA ELGADY/HEAT PAPER 336 Some water is heated electrically in a glass beaker in an experiment to find the specific heat

capacity of water. The temperature of the water is taken at regular intervals.

The temperature-time graph for this heating is shown in Fig. 4.1.

ForExaminer’s

Use

60temperature / °C

50

40

30

20

10

00 60 120 180 240 300

time /s

Fig. 4.1

(a) (i) Use the graph to find1. the temperature rise in the first 120s,

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

2. the temperature rise in the second 120s interval.............................

(ii) Explain why these values are different.

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

............................................................................................................................ ......[2]

(b) The experiment is repeated in an insulated beaker. This time, the temperature of thewater increases from 20°C to 60°C in 210s. The beaker contains 75g of water. Thepower of the heater is 60W. Calculate the specific heat capacity of water.

specific heat capacity = ........................[4]

ForExaminer’s

Use

12

ForExaminer’s

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12MS.RAJA ELGADY/HEAT PAPER 3(c) In order to measure the temperature during the heating, a thermocouple is used.

Draw a labelled diagram of a thermocouple connected to measure temperature.For

Examiner’sUse

[2]

ForExaminer’s

Use

13

ForExaminer’s

Use


ForExaminer’s

Use

14

ForExaminer’s

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14MS.RAJA ELGADY/HEAT PAPER 337- Fig. 4.1 shows apparatus that a student uses to make an estimate of the specific heat

capacity of iron.

ForExaminer’s

Use

thermometer electrical heater

iron block

Fig. 4.1

(a) The power of the heater is known. State the four readings the student must take to findthe specific heat capacity of iron.

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

2. ........................................................................................................................... ...........

3. ..................................................................................................................... .................

4. ........................................................................................................................... ...... [3]

(b) Write down an equation, in words or in symbols, that could be used to work out thespecific heat capacity of iron from the readings in (a).

[2]

ForExaminer’s

Use

15

ForExaminer’s

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ForExaminer’s

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16

ForExaminer’s

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16MS.RAJA ELGADY/HEAT PAPER 3(c) (i) Explain why the value obtained with this apparatus is higher than the actual value.

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

........................................................................................................................... ... [1]

(ii) State one addition to the apparatus that would help to improve the accuracy of thevalue obtained.

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

............................................................................................................................. . [1]

5

ForExaminer’s

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17

ForExaminer’s

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17MS.RAJA ELGADY/HEAT PAPER 337-(a) Fig. 5.1 shows the paths of a few air molecules and a single dust particle. The actual air

molecules are too small to show on the diagram. ForExaminer’s

Use

paths ofair molecules

dust particle

Fig. 5.1

Explain why the dust particle undergoes small random movements.

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

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

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

............................................................................................................................. ........ [4]

(b) Fig. 5.2 shows the paths of a few molecules leaving the surface of a liquid. The liquid isbelow its boiling point.

air and vapourliquid

Fig. 5.2

(i) State which liquid molecules are most likely to leave the surface.

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

............................................................................................................................. . [1]

(ii) Explain your answer to (i).

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

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

.............................................................................................................................. [2]

MS.RAJA ELGADY/HEAT PAPER 338- (a) (i) State two ways in which the molecular structure of a liquid is different from the molecular

structure of a solid.

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

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

2. ................................................................................................................ .......................

............................................................................................................................. ..............[2]

(ii) Explain, in terms of energy, the process which takes place as a solid at its melting pointchanges into a liquid at the same temperature.

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

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

............................................................................................................................. ......... [1]

(b) During a severe snowstorm, a layer of snow (ice crystals) forms on the body of an animal in afield. The snow and the surrounding air are at 0°C. The snow begins to melt.

(i) The mass of snow that falls on the animal is 1.65kg. The specific latent heat of fusion ofsnow is 330000J/kg.

Calculate the thermal energy needed to melt this snow.

thermal energy = ............................................... [2]

(ii) The animal derives energy from its food to maintain its body temperature.

State the energy change that takes place.

............................................................................................................................. ......... [1] [Total: 6]

11 A mass of 0.36kg of a certain substance is in the solid state in a well-insulated container. Thesubstance is heated at the rate of 1.2 × 104 J /minute.

2.0 minutes after starting the heating, the substance is all at the same temperature, and it starts tomelt.

11.0 minutes after starting the heating, the substance finishes melting and the temperature startsto rise again.

(a) Calculate the specific latent heat of the substance.

MS.RAJA ELGADY/HEAT PAPER 3specific latent heat = ...........................................................[3]

(b) (i) After 11 minutes of heating, when the temperature starts rising again, in which state isthe substance?

............................................................................................................................. ..........[1]

(ii) Describe what happens to the molecules as thermal energy is supplied to them in thisstate.

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

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

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

............................................................................................................................. ..........[2] [Total: 6]

39- A student in a laboratory uses the apparatus shown in Fig. 4.1 to determine the specific heatcapacity of aluminium.

to low voltage supplyand measuring instruments

thermometer

electrical heater

aluminium block

Fig. 4.1

The readings obtained in the experiment are given below.

mass of aluminium block = 0.930kg

initial temperature of block = 13.1°C

final temperature of block = 41.3°C

electrical energy supplied = 23 800J

MS.RAJA ELGADY/HEAT PAPER 3(a) Define specific heat capacity.

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

........................................................................................................... .................................. [2]

(b) Use the readings above to calculate the specific heat capacity of aluminium.

State the equation you use.

specific heat capacity = ......................................................... [3]

MS.RAJA ELGADY/HEAT PAPER 3(c) Because the student knows it is good scientific practice to repeat readings,

after a short time he carries out the experiment again, supplying the samequantity of electrical energy.

This time the temperature readings are:

initial temperature of block = 41.0°C

final temperature of block = 62.1°C

(i) Use these figures to calculate a second value for the specificheat capacity of aluminium.

specific heat capacity = ......................................................... [1]

(ii) The student did not make any mistakes when taking the readings.

Suggest why the second value for the specific heat capacity of thealuminium is greater than the first.

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

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

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

................. [2]

(d) Suggest two ways of improving the experiment in order to give asaccurate a result as possible.

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

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

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

2................................................................................................................................................

MS.RAJA ELGADY/HEAT PAPER 3.............................................................................................................................................. [2] [Total: 1

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