CHAPTER 4: HEAT

SPM 2003,Section C, No. 3 [20 Marks]1 You are representing the country in carrying out a research project on the weather at the

North Pole. The surrounding temperature is between -400C to -80C. One item of the equipment to be taken for your research is a thermometer.

(a) State the principle used in a liquid-glass thermometer.[1 mark]

(b) State how a liquid-glass thermometer can be used to measure the body temperature ofa sick person. Explain heat transfer that takes place at each stage of measurement.

[4 marks](c) The table shows the characteristics of six types of thermometer P, Q, R, S, T and U.

ThermometerLiquidused

Glasswalled bulb

Diameter of capillary

tube

Glass-bore stem

Cross-section

P mercury thin bigthick and curved

Q mercury thick small thin and plane

R mercury thin small thin and curve

S alcohol thick big thick and plane

T alcohol thin smallthick and curved

U alcohol thick small thin and plane

Additional information:Freezing point of mercury = -390C Boiling point of mercury = 3600CFreezing point of alcohol = -1120C Boiling point of alcohol = 780C

Based on the table above

(i) Explain the suitable characteristics of the thermometer so that it can be used to measure temperature at the North Pole.

(ii) Decide which thermometer is most suitable to be taken for your research and give reasons.

[10 marks]

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(d) A thermometer which is not calibrated has a mercury column of length 8.0 cm when the temperature is 00C and 20.0 cm when the temperature is 1000C. The mercury column is 5.0 cm when put in liquid X.

(i) Determine the temperature of liquid X in Kelvin(ii) State a thermometric property used when making of a thermometer.

[5 marks]

SPM 2004 , Section C , No. 11 [20 Marks]2 (a)Figure 3.1 shows a food container used for keeping food warm. The container is able to

maintain the temperature of food for a long time. The container can be moved from one place to another.

Figure 3.1

Table 3.1 shows the characteristics of materials which could be used to make the food container.Characteristic

Material

Density / kg m-3 Melting Point / 0C

Specific heat capacity / J kg-1

0C-1

Thermal conductivity

P 2 710 660 910 HighQ 910 27 1 600 LowR 1 050 240 1 300 LowS 2 600 1 200 670 LowT 3 800 2 020 800 HIgh

(i) What is meant by melting point ?[1 mark]

(ii) Your are asked to investigate the characteristics of the material in Table 3.1 Which

could be used to make the food container as in Figure 3.1 Explain the suitability of each characteristics in Table 3.1 and hence, determine Which material is most suitable to be used to make the food container. Justify your choice.

[10 marks]

(b) 500 g of hot water at 90 0C is poured into a glass and left to cool down to room temperature at 30 0C.

(i) Sketch the temperature-time graph for the cooling process of the hot water. Use your graph to explain this process.

[4 marks]

(ii) Calculate the quantity of heat lost from the hot water. The specific heat capacity of water is 4 200 J kg-10C-1.

[2 marks]

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(iii) Hot water is poured into a glass which has a small crack. It is observed that the size of the crack increases.

Explain this observation.[3 marks]

SPM 2006 Section C, No. 11 [20 Marks]3 (a)(i) What is meant by specific latent heat of vaporization?

[1 mark]

(ii)Explain why someone who is sweating feels cool when he is under a rotating fan.[4 marks]

(b) A solid substance, of mass 0.05 kg, is heated using an immersion heater of 240 V,0.1 kW. Diagram 11.1 shows the heating curve of the solid.

Temperature / 0C

Diagram 11.1

Calculate(i) The specific latent heat of fusion of the substances,(ii) The specific latent heat capacity of the substances in liquid state.

[5 marks]

(c) Your are asked to investigate the features of cooling material and the design of a car engine radiator as in Diagram 11.2. Explain the suitability of each features in Diagram 11.2 and then determine the most suitable car engine radiator to be used. Give a reason for your choice.

[10 marks]

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Time / min

P

The features of cooling liquid

Boiling point 100 0C Specific heat capacity 4 200 J

kg-1 C-1

Q

The features of cooling liquid

Boiling point 100 0C Specific heat capacity 4 200 J

kg-1 C-1

R

The features of cooling liquid

Boiling point 100 0C Specific heat capacity 4 200 J

kg-1 C-1

S

The features of cooling liquid

Boiling point 78 0C Specific heat capacity 2 450 J

kg-1 C-1

T

The features of cooling liquid

Boiling point 78 0C Specific heat capacity 2 450 J

kg-1 C-1

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