ce physics 2002 paper2(e)

香港考試局保留版權

Hong Kong Examinations Authority All Rights Reserved 2002 2002-CE-PHY 2–1

HONG KONG EXAMINATIONS AUTHORITY

HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 2002

PHYSICS PAPER 2

10.45 am – 11.45 am (1 hour)

1. Read carefully the instructions on the Answer Sheet and insert the information

required (including the Subject Code) in the spaces provided. 2. When told to open this book, you should check that all the questions are there.

Look for the words ‘END OF PAPER’ after the last question. 3. All questions carry equal marks. 4. ANSWER ALL QUESTIONS. You should mark all your answers on the

Answer Sheet. 5. You should mark only ONE answer for each question. If you mark more than

one answer, you will receive NO MARKS for that question. 6. No marks will be deducted for wrong answers.

Subject Code 170

2002-CE PHY 2

2002-CE-PHY 2–2 – 1 – 保留版權 All Rights Reserved 2002

There are 45 questions. The last page of this question paper contains a list of physics formulae which you may find useful.

If necessary, take g = 10 m s–2. Unless otherwise specified, all the cells are assumed to have negligible internal resistance.

1. The figure above shows the distance-time graphs of two toy cars P and Q

moving along a linear track. Which of the following statements are correct ? (1) Car P will reach the 20 m-mark first. (2) Car P is overtaking car Q at t = 5 s. (3) The average speed of car P in the first 5 s is smaller than that of

car Q. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 2.

The figure above shows the variation of the resultant force acting on an object with time. What physical quantity does the area of the shaded region represent ? A. acceleration B. change of momentum

C. work D. power

50

s/m

t/s

P Q20

Resultant force

Time 0


Go on to the next page

3. A piece of stone is hung from a balloon, which is rising vertically upward. If the string connecting the stone and the balloon suddenly breaks, which of the following velocity-time graphs represents the subsequent motion of the stone ? [Note : Velocity pointing upward is taken to be positive.]

A. B. C. D. 4. The following are statements written by three students about Newton’s first

law of motion. (1) A stationary object will remain in a state of rest unless acted on by

an unbalanced force. (2) An object undergoing uniform motion will maintain its motion

unless acted on by an unbalanced force. (3) An unbalanced force is required to maintain the motion of an object

at uniform velocity. Which of the above statements is/are correct ? A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only

0

v

t 0

v

t

0

v

t 0

v

t

2002-CE-PHY 2–4 – 3– 保留版權 All Rights Reserved 2002

5. Which of the following objects are under the action of an unbalanced force at the instant shown in the diagrams ?

(1) a football being kicked by a

player (2) a parachutist falling with

uniform velocity

(3) a swinging pendulum bob

A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

6. A block of mass 0.5 kg slides down a rough inclined plane with an

acceleration of 3 m s–2. If the plane is inclined at 30° to the horizontal, find the friction between the block and the plane.

A. 1 N B. 1.5 N C. 2.8 N D. 4 N

30°



7. John, of mass 80 kg, is standing on a weighing scale in a lift. At a certain instant, the reading of the weighing scale is 600 N. Which of the following statements about John at this instant is/are correct ?

(1) The gravitational force acting on John is 600 N. (2) The force exerted by the weighing scale on John is 200 N. (3) John is accelerating downward at a rate of 2.5 m s–2. A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only 8.

A block is projected up a smooth inclined plane. Which of the following graphs shows the variation of the kinetic energy (K.E.) of the block with its potential energy (P.E.) during the upward motion ? A. B. C. D.

K.E.

P.E.0

K.E.

P.E. 0

K.E.

P.E.0

K.E.

P.E. 0


9.

A block of weight 100 N is placed on a smooth horizontal table. A vertical force of 60 N and a horizontal force of 30 N are applied to the block as shown. Find the magnitude of the resultant force acting on the block. A. 30 N B. 40 N C. 50 N

D. 67 N 10. The figure above shows a flying wheel in an amusement park. The wheel is

of diameter 18 m and carries eight cages. There is only one passenger of mass 60 kg inside one of the cages. The wheel rotates with uniform speed and it takes 80 s for the passenger to travel from the bottom to the top of the wheel. Find the average useful power output of the motor of the wheel.

A. W)181060( ××

B. W)80

181060( ××

C. W)80

91060( ××× π

D. W)8091060( ×××× π

60 N

30 N



11. (1) (2) (3)

A block is initially at rest on smooth horizontal ground. Two forces of equal magnitude F act on the block. In which of the above cases will the block remain at rest ? A. (2) only B. (3) only

C. (1) and (2) only D. (1) and (3) only

12. Grace and Kitty, of masses 50 kg and 40 kg respectively, stand on light

rollers on a smooth horizontal floor. They are initially at rest with Grace holding a 2 kg ball. Grace throws the ball to Kitty and moves backward with a speed 0.8 m s–1 afterwards. After catching the ball, Kitty moves in the opposite direction as shown above. Which of the following statements is/are correct ?

(1) The final speed of Kitty is 0.95 m s–1. (2) The horizontal momentum of the ball is conserved in this

process. (3) The total kinetic energy of Kitty and the ball decreases when

Kitty catches the ball. A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only

Kitty Grace

0.8 m s–1

F

F

F F

F F


13. A microwave receiver is installed in front of a concave reflector. At which

position should the receiver be installed in order to ensure the best reception of microwaves ?

A. at the centre of curvature of the reflector B. at the focus of the reflector C. at the pole of the reflector D. at the mid-point between the pole and the focus of the

reflector 14. A ray of light travels in air and strikes a glass block as shown above. Which

of the following diagrams best shows the path of the ray ? A. B. C. D.

Receiver



15. Which of the following statements about the properties of virtual images formed in spherical mirrors is incorrect ?

A. Virtual images can be seen by observers. B. Virtual images always lie behind the mirror. C. Virtual images are always erect. D. Virtual images are always magnified. 16.

A man places his spectacles on a book as shown above. What kind of lenses

does he wear and what defect of vision does he have ? Lenses Defect of vision A. converging lenses long-sightedness B. converging lenses short-sightedness C. diverging lenses long-sightedness D. diverging lenses short-sightedness


(For Questions 17 and 18.) A cup is placed in front of a window, outside which is a distant building. Two photos P1 and P2 as shown below are taken with the same single-lens camera.

17. Which of the following ray diagrams correctly shows how the image I of

the cup O is formed by the lens of the camera in photo P1 ? C. D. 18. Which of the following statements about the two photos must be correct ? A. In P1, the images of the cup and the building are on

different sides of the lens of the camera. B. In P1, the image of the cup is real while that of the

building is virtual. C. On taking P2, the distance between the lens and the film of

the camera is shorter than that on taking P1. D. After taking P1, the photographer has to move forward in

order to take P2.

Photo P1 Photo P2

OI

O O

O

I

I I

A. B.



19. A certain amount of crushed solid is heated and the variation of its

temperature with time is shown above. If the same heater is used to heat a smaller amount of the solid, which of the following graphs (in dash lines) best shows the variation of the temperature of the solid ?

A. B. C. D.

Temperature

Time0

Temperature

Time0

Temperature

Time 0

Temperature

Time0

Temperature

Time 0


(For Questions 20 and 21.) The specific heat capacity of a metal is measured using the following method: A metal block is first immersed in boiling water for some time. The block is then transferred to a cup of cold water. After a while, the temperature of the water is measured. 20. The result of the experiment is as follows: Mass of metal block = 0.8 kg Mass of water in the cup = 0.3 kg Initial temperature of water in the cup = 23°C Final temperature of water in the cup = 38°C Find the specific heat capacity of the metal (in J kg–1 K–1). (Given : Specific heat capacity of water = 4200 J kg–1 K–1.) A. 236 B. 381 C. 622 D. 953 21. The result obtained in Q.20 is found to be higher than the true value of the

specific heat capacity of the metal. Which of the following is a probable reason ?

A. Some hot water is still adhered to the metal block when

the block is transferred to the cold water. B. Some energy is lost to the surroundings when the metal

block is transferred to the cold water. C. Some energy is absorbed by the cup. D. The temperature of the metal block is still higher than

38°C when the final temperature of the water in the cup is measured.

Beaker

Metal block Boiling water

Heater

Hot metal block

Cup

Cold water Thermometer

Step 2: Step 1:



22.

The above graph shows the result obtained when an experiment is

performed to study the relation between the pressure and temperature of a fixed mass of gas at constant volume. Which of the following statements is/are correct ?

(1) The y- and x-axes denote the pressure and temperature of the gas

respectively. (2) The slope of the graph denotes the volume of the gas. (3) The intercept y0 denotes the absolute zero temperature.

A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

23. A column of gas is trapped inside a cylinder. The piston is now pushed

slowly causing the gas to be compressed at a constant temperature. Which of the following statements about the gas molecules in the cylinder is/are correct ?

(1) The average speed of the gas molecules increases. (2) Each gas molecule exerts a greater impact force on the walls of the

cylinder in each collision. (3) The gas molecules collide more frequently with the walls of the

cylinder. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only

x

y

y0

0

Piston

Gas

Cylinder


24. In a ripple tank experiment, a series of water waves travels towards a barrier. Which of the following quantities would remain unchanged after the waves are reflected by the barrier ?

(1) wavelength (2) frequency (3) speed A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 25. A wave source generates waves of frequency 50 Hz. How long does it take

for the waves to travel 100 m ? A. 0.5 s B. 2 s C. 5000 s D. It cannot be determined as insufficient information is

given. 26. Which of the following phenomena would be observed when the water

waves pass through the opening in the above set-up ? A. reflection B. refraction C. diffraction D. interference

Ripple tank

Spongy lining

Plane water waves

Opening



27. Which of the following is/are the reason(s) for not over-using ultra-violet lamps to produce a suntan effect ?

(1) Ultra-violet radiation is highly penetrating and will damage body

tissue. (2) Ultra-violet radiation has a strong heating effect and will damage

body tissue. (3) Over exposure to ultra-violet radiation may cause skin cancer. A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only 28.

The figure above shows the image of a foetus (a baby not yet born) taken by a scanner. Which of the following waves should be used in the scanning process ? A. infra-red B. microwaves C. ultrasonics D. X-rays


29.

The above figures show the CRO displays of two musical notes X and Y. The settings of the CRO for displaying the two notes are identical. Which of the following statements are correct ?

(1) Notes X and Y are of different qualities. (2) Note X is of a higher pitch than note Y. (3) Note X is louder than note Y. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) 30. In the above circuit, both ammeters A1 and A2 read 1 A when switch S is

open. Find the readings of the two ammeters when S is closed. A1 A2 A. 0.5 A 1.5 A B. 0.67 A 1 A C. 1 A 1.5 A D. 1 A 3 A

Note X Note Y

A

A

3 Ω

6 Ω

S

A1

A2



A plastic ruler is placed close to a stream of running water coming from an

insulated tap. The stream of water is attracted towards the ruler as shown above. Which of the following statements are correct ?

(1) The ruler carries an electric charge. (2) The ruler and the running water are attracting each other with

forces of equal magnitude. (3) Both positive and negative charges are induced on the running

water. A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only

E. (1), (2) and (3) F.

32. P, Q and R are three parallel straight wires carrying equal currents flowing

out of the paper. R is equidistant from P and Q. What is the direction of the resultant force acting on R by P and Q ?

A. → B. ← C. D.

P

R

Q

↑ ↓

31.


33. The figure above shows the voltage-current (V-I ) graphs of two resistors X

and Y. Which of the following deductions is/are correct ? (1) The resistance of X is higher than that of Y. (2) If X and Y are connected in series, the V-I graph of the combined

resistor will lie in region P. (3) If X and Y are connected in parallel, the V-I graph of the combined

resistor will lie in region Q. A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only 34. Three identical lamps L1, L2 and L3 of ratings ‘6 V, 12 W’ are connected to a

6 V battery as shown above. Which of the following statements is correct ? A. The potential difference across L2 is 3 V. B. The current passing through L1 is 2 A. C. The total power drawn from the battery is 12 W. D. The total power dissipated in L1 and L2 is smaller than

that in L3.

V

I

X

0

Region P

Y

Region Q

L1 L3

L2

6 V



35. Which of the above circuits can be used to find the resistance of the resistor

R, by taking the ammeter and voltmeter readings ? A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3)

A

V

2 Ω R

Circuit (1)

A

V

2 Ω R

Circuit (2)

A

V

2 Ω R

Circuit (3)


36.

If the live and neutral wires of an electric kettle are mistakenly interchanged

inside the plug as shown above, which of the following will happen ? A. The kettle will not operate. B. The fuse of the kettle will blow. C. The metal case of the kettle will still stand at a high

potential even when the switch of the kettle is off. D. The heating element of the kettle will still stand at a high

potential even when the switch of the kettle is off. 37. Which of the following shows how a moving-coil galvanometer can be

converted into a voltmeter ? A. B. C. D.

1000 Ω 1 Ω

1000 Ω 1 Ω

Neutral wire

Live wire



38. The figure above shows a model power line. An a.c. supply and two ideal

transformers are used to operate a lamp of rating ‘6 V, 24 W’. The total resistance of the cables AB and CD is 10 Ω. If the lamp operates at its rated value, find the power loss in the cables.

A. 0.4 W B. 3.6 W C. 160 W D. 1440 W 39. The above diagram shows the circuit of the starter motor of a car. When the

starter switch is closed, a small current flows through device X and a large current then flows through the motor and starts it. What is device X ?

A. a transformer B. a reed relay C. a thermistor D. a logic gate

M

Starter switch

X

A B

C D

6V 24 W

20 : 1 step-down transformer

1 : 20 step-uptransformer


40. A radioactive isotope Th23490 undergoes a series of decay processes to form

a daughter nuclide Pb20682 . How many α-particles and β-particles have been

emitted in this decay process ? No. of α-particles No. of β-particles A. 6 7 B. 7 6 C. 7 8 D. 8 7 41. Which of the following particles cannot be deflected by a magnetic field ? A. α-particles B. β-particles C. neutrons D. protons 42. Which of the following is/are application(s) of radioactivity ?

(1) to estimate the age of ancient remains (2) to kill bacteria in food (3) to transmit signals over long distances

A. (2) only B. (3) only C. (1) and (2) only D. (1) and (3) only


Directions : Each question below (questions 43 – 45) consists of two statements. Decide whether each of the two statements is true or false. If both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option A, B, C or D according to the following table :

1st statement 2nd statement

A. True True The 2nd statement is a correct explanation of

the 1st statement B. True True The 2nd statement is not a correct explanation

of the 1st statement C. True False D. False True

1st statement 2nd statement 43. Air-cushioned sports shoes can

reduce the impact force acting on the feet during jumping andrunning.

Air-cushioned sports shoes can increase the time of impact between the feet and the ground during jumping and running.

44. A transformer can be used to step

up the power of an a.c. supply. A transformer can be used to step

up the voltage of an a.c. supply. 45. A lightning conductor can protect a

building from being damaged by lightning during a thunderstorm.

As the lightning conductor and the thundercloud carry like charges, there is a strong repulsion between them.

END OF PAPER


Useful Formulae in Physics

(a) Relationships between initial velocity u, uniform acceleration a, final velocity v and displacement travelled s after time t :

v u + at=

s ut + at=12

2

2 2 2v u + as= (b) Potential energy gained by a body of mass m when raised through a height h is mgh. (c) Kinetic energy of a body of mass m moving with speed v is

12

2mv .

(d) Power = force × velocity (e) Equivalent resistance of two resistors R1 and R2 : (i) in series R + R= 1 2

(ii) in parallelR R

R R=

+1 2

1 2

(f) Power = potential difference × current

2002-CE-PHY 2–25 – 24– 保留版權 All Rights Reserved 2002

2002 Physics Paper 2

Question No. Key Question No. Key

1. A (48) 26. C (87) 2. B (50) 27. B (41) 3. C (42) 28. C (89) 4. C (75) 29. B (63) 5. B (55) 30. C (57)

6. A (57) 31. D (27) 7. B (48) 32. D (42) 8. C (48) 33. B (48) 9. A (17) 34. D (44) 10. B (43) 35. C (46)

11. A (64) 36. D (54) 12. D (21) 37. A (51) 13. B (74) 38. A (28) 14. D (80) 39. B (75) 15. D (61) 40. B (70)

16. D (58) 41. C (84) 17. A (53) 42. C (61) 18. C (53) 43. A (71) 19. C (69) 44. D (60) 20. B (56) 45. C (69)

21. A (19) 22. A (64) 23. B (49) 24. D (74) 25. D (62)

Note: Figures in brackets indicate the percentages of candidates choosing the

correct answers.

ce physics 2002 paper2(e)

Health & Medicine

cushioned

specific heat

resultant

unbalanced

kinetic energy

high potential

kg1 k1

violet radiation