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Sha Tin Methodist College

First Examination (2009-2010)

Physics

Form Three Name : ______________________

Time allowed : 45 minutes Class : _______________ ( )

Full mark : 50

Instructions to students:

1. This paper consists of TWO sections, A and B.

2. Answer ALL questions in the answer sheet provided.

3. There are 20 multiple-choice questions in Section A and each carries 1mark.

4. There are 4 long questions in Section B and carries 30 marks.

5. All questions should be answered on the Answered Sheet.

Useful Formulae

100

0100

0

=

ll

llT

T

E= P t

E= mc T

Given: Specific heat capacity of water is 4200 J kg-1 oC-1

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Section A: Multiple Choice Questions (20 marks)

1. When the temperature of a metal block increases,

A the size of its particles increases.

B its particles move more vigorously.

C the average kinetic energy of its particles remains unchanged.

D the number of its particles increases.

2. Some materials expand with temperature. Which of the following thermometers make(s) use of

this property to measure temperature?

(1) Liquid-in-glass thermometer

(2) Liquid crystal thermometer

(3) Rotary thermometerA (1) only

B (2) only

C (1) and (3) only

D (2) and (3) only

3. An iron spoon at 20 C is put into water at 80 C. Which of the following statements are correct?

(1) The specific heat capacity of the water decreases while that of the iron spoon increases.

(2) The average kinetic energy of the particles in the water decreases while that in the iron spoon

increases.

(3) The water and the iron spoon will have the same temperature eventually.

A (1) and (2) only

B (1) and (3) only

C (2) and (3) only

D (1), (2) and (3)

.

4. A light bulb of power 100 W is switched on for 4 minutes. How much

energy is given out by the light bulb?

A 100 J

B 400 J

C 6000 J

D 24 000 J

5. A heater immersed in water is connected to a kilowatt-hour meter. It is found that 0.15 kW h is

used by the heater. If half of the energy is lost to the surroundings, what is the total energy gained

by the water?

A 75 J

B 150 J

C 4500 J

D 270 kJ

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6. Which of the following is a unit of heat capacity?

A J

B J kg1C1

C JC

1

D J C

7. Which of the following are related to the high specific heat capacity of water?

(1) Water is used as a coolant in motor cars.

(2) Coastal areas have a smaller temperature change throughout a day.

(3) The temperature of our body changes more slowly than the temperature of the surroundings.

A (1) and (2) only

B (1) and (3) only

C (2) and (3) only

D (1), (2) and (3)

8. An immersion heater of power 150 W is switched on for 2 minutes. How much energy is given out

by the heater?

A 150 J

B 300 J

C 18 kJ

D 30 kJ

9. A heater supplies 1000 J of energy to a 5-kg metal block. The temperature of that metal block rises

from 25 C to 35 C. Assume that there is no energy loss to the surroundings. What is the heat

capacity of the metal block?

A 20 J C1

B 50 J C1

C 100 J C1

D 200 J C1

10. LiquidsX, YandZof equal mass are heated separately by three identical heaters. The graph shows

the variation of the temperatures of the liquids with time. Let cX, cY and cZ be the specific heat

capacities ofX, YandZrespectively. Which of the following relations is correct?

A cX= cY > cZ

3

temperature

time

Z

Y

X

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B cX> cY > cZ

C cX> cY = cZ

D cX< cY = cZ

11. Which of the following statements about the internal energy and temperature of two objects is/are

correct?(1) The object with larger internal energy must have a higher temperature.

(2) The object with particles of larger average kinetic energy must have a higher temperature.

(3) When the objects are in contact, heat is transferred from the one with larger internal energy to

the other.

A (1) only

B (2) only

C (1) and (3) only

D (2) and (3) only

12. A metal block of mass 0.1 kg at 150 C is put in water of mass 1 kg at 20 C. If the heat capacity of

the metal block is 100 J C1, which of the following is the final temperature of the mixture?

(Specific heat capacity of water = 4200 J kg1C1)

A 20.3 C

B 23.0 C

C 85 C

D Cannot be determined

13. Which of the following substances has the highest specific heat capacity?

A 1 kg of water at 95 C

B 2 kg of water at 70 C

C 3 kg of water at 65 C

D All the substances above have the same specific heat capacity.

14. A 5-kg metal block is heated by a heater of power 1 kW for 3 minutes. The temperature of the

metal block rises from 12 C to 87 C. What is the specific heat capacity of the metal block?

A 240 J kg1 C1

B 480 J kg1 C1

C 1200 J kg1 C1

D 2400 J kg1 C1

15. Aluminium melts at 660 C. Its specific latent heat of fusion is 3.9 105 J kg1. Find the energy

required for melting 200 g of aluminium at its melting point.

A 0.2 3.9 105 J

B J0.2

103.95

C J6600.2

103.95

D 0.2 3.9 105 660 J

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temperature / C

time / mint1

t2

16. Which of the following cannot increase the rate of evaporation of water?A Increase the surface area of water

B Speed up the movement of air

C Decrease the temperature of water

D Decrease the humidity of air

17. Which of the following is not the difference between boiling and evaporation?

A Latent heat of vaporization is needed in boiling, but not in evaporation.

B Boiling occurs at a definite temperature but evaporation does not.

C Boiling takes place within the whole liquid, but evaporation occurs at the surface of liquid.

D Bubbles are formed violently in boiling, but no bubble is formed in evaporation.

18. The temperaturetime graph of a material is recorded as follows.

Which of the following descriptions about the material during t1 and t2 is/are correct?

(1) Its temperature remains unchanged.

(2) Its state of matter remains unchanged.

(3) Its internal energy remains unchanged.

A (1) only

B (1) and (3) only

C (2) and (3) only

D (1), (2) and (3)

19. Ice cubes of mass 25 g at 0 C are dropped into a beaker containing 250 g of water at 40 C. What

is the final temperature of the mixture? Assume that no energy is lost to the surroundings.

(Specific latent heat of fusion of ice = 3.34 105 J kg1

Specific heat capacity of water = 4200 J kg1)

A 20.0 C

B 25.0 C

C 29.1 C

D 32.2 C

20. There is a cup of water on the table. Which of the following statements are correct?

(1) The average kinetic energy of the water particles in the cup decreases as the water

evaporates.

(2) Evaporation takes place only when the water temperature is higher than the room

temperature.

(3) Water absorbs energy when it boils as well as evaporates.

A (1) and (2) only

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B (1) and (3) only

C (2) and (3) only

D (1), (2) and (3)

--- End of Section A ---

Section BLong Questions (30 marks)

21. Three beakers with water are shown below.

(a) Which beaker contains greatest internal energy? (1 mark)

(b) In which two beakers that the water particles motion is the same? Why? (2 marks)

(c) Write ONE similarity and ONE difference between the water particles beaker A and C.

(2 marks)22. Why will watermelon stay cooler for a longer time than sandwiches when both are removed from

the same refrigerator on a hot day? (3 marks)

23. A cooling curve of an unknown substanceXis shown.

(a) Estimate the melting point of substanceX. (1 mark)

(b) Why the temperature does not drop even substanceX

lose energy during the time equals to 4to 11 minutes? (2 marks)

(c) Another unknown substance Yis also brought to cool. IfYhas

(i) the same starting temperature asX,

(ii) lower melting point than that ofX, and

(iii) greater latent heat than that ofX,

sketch the cooling curve ofYon space provided on the answer sheet. (3 marks)

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24. The below set-up is used to measure specific heat capacity of a metal block.

(a) Decide whether the following statements are correct or not. (4 marks)

(i) Temperature of metal block will not be everywhere the same because there is no stirring.

(ii) Wrap the metal block with towel can reduce heat lost.

(iii) The polystyrene plate can be replaced by wooden plate.

(iv) Usually a smaller measured value of specific heat capacity will be obtained in this

experiment.

(b) Can we improve the experimental result by using larger metal block (while all factors in theexperiment remained unchanged)? Explain your answer. (2 marks)

25. The below set-up is used to measure the specific latent heat of vaporization of liquid.

There is a disc which can turn in apparatusX. Each revolution represents 5000J.

The result of experiment as follows:

Mass of liquid used at the beginning of the experiment 1800g

Mass of liquid left after the end of the experiment 1650g

No. of revolutions made by the disc of apparatusX 97

(a) Name the apparatusXand state its function. (2 marks)

(b) What mass should be used for the calculation of the specific latent heat of vaporization here?

(1 mark)

(c) Calculate the specific latent heat of vaporization of the liquid. (3 marks)

(d) Can the experimental result be improved by putting a lid over the cup? Explain your answer.

(2 marks)

(e) Write down ONE error source for higher and lower measured value respectively. (2 marks)

--- End of paper ---Setter : M.K. Lam

7

to power supply

and joulemeter

immersion heater metal block

polystyrene plate

thermometer

cup

electronic balanceimmersion

heater

Apparatus X

power supplyliquid

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Sha Tin Methodist College

First Term Examination (2009-2010)

Physics

Answer Sheet

Form Three Name : ________________

Time allowed : 45 minutes Class : ___________ ( )

Full mark : 50

Section A: 20 marks

Put a tick in the box of answer.

1 2 3 4 5 6 7 8 9 10

A

BC

D

11 12 13 14 15 16 17 18 19 20

A

B

C

D

Section B: 30 marks

21. (a) Beaker _________________________________________________________________

(b) Beakers ________________________________________________________________

It is because _____________________________________________________________

_______________________________________________________________________

(c) Similarity: ______________________________________________________________

_______________________________________________________________________

Difference: ______________________________________________________________

_______________________________________________________________________

22. __________________________________________________________________________

__________________________________________________________________________

__________________________________________________________________________

23. (a) The melting point ofX: ____________________________________________________

8

20

8

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(b) _______________________________________________________________________

_______________________________________________________________________

. (c)

Circle the correct answer in 24 (a), 24 (b), 25 (b) and 25 (d).

24. (a) (i) Correct / Incorrect (ii) Correct / Incorrect

(iii) Correct / Incorrect (iv) Correct / Incorrect

(b) It (can / cannot) improve the experiment. It is because

________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

25. (a) Apparatus Xis ______________________________________________________________

Its function is _______________________________________________________________

(b) We should measure the mass of (liquid used / liquid left / liquid used liquid left).

(c) ___________________________________________________________________________

___________________________________________________________________________

(d) It (can / cannot) improve the experiment. It is because

________________________________

___________________________________________________________________________

___________________________________________________________________________

(e) Error source for

higher measured value:

_______________________________________________________ ,

lower measured value :

________________________________________________________

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--- End of paper ---

Setter : M.K. Lam

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