2001-CE PHY 2 HONG KONG EXAMINATIONS AUTHORITY HONG KONG CERTIFICATE OF EDUCATION EXAMINATION 2001 PHYSICS PAPER 2 10.45 am 11.45 am (1 hour) Subject Code 170 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. 香港考試局保留版權 Hong Kong Examinations Authority All Rights Reserved 2001 2001-CE-PHY 2 1
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. Distance from P 0 Time A car travels along a straight road. The variation of the distance of the car from a fixed point P on the road with time is shown above. Which of the following statements is correct? A. The speed of the car is decreasing. B. The car is moving towards P. C. There is an unbalanced force acting on the car. D. The area under the graph denotes the total distance travelled by the car. E. The slope of the graph denotes the acceleration of the car. 2. A girl walks along a straight road from a point A to a point B with an average speed 1 m s 1. She then returns from B to A along the same road with an average speed 2 m s 1. Find the average speed of the girl for the whole journey. A. zero B. 0.67 m s 1 C. 1.33 m s 1 D. 1.41 m s 1 E. 1.50 m s 1 2001-CE-PHY 2 2 1
3. A stone is thrown vertically upwards. Assuming air resistance is negligible, which of the following statements is/are correct? 4. (1) The acceleration of the stone decreases throughout the upward motion. (2) The net force acting on the stone becomes zero when the stone reaches the highest point. (3) The total energy of the stone remains unchanged throughout the motion. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) A coin is placed on a piece of cardboard resting on a glass as shown above. If the cardboard is flicked off sharply with a finger, the coin will drop into the glass. What does this experiment demonstrate? A. The coin will fall with uniform acceleration under the action of gravity. B. The acceleration of the coin is proportional to the applied force. C. Action and reaction always occur in pairs. D. Momentum is conserved in a collision. E. The coin has a tendency to maintain its state of rest. 2001-CE-PHY 2 3 2 Go on to the next page
5. 10 N 2 N A block on a rough horizontal table is acted on by two horizontal forces of magnitudes 10 N and 2 N as shown. It remains at rest on the table. If the force of magnitude 10 N is removed, find the resultant force acting on the block. A. zero B. 2 N C. 6 N D. 8 N E. 10 N 6. X Y 450N 1.5 m 5 m 1.5 m A uniform plank of weight 450 N rests on two trestles X and Y and a worker of weight 675 N stands at one end of the plank as shown above. The worker holds a light basket which contains several packets of goods each of weight 6 N. What is the maximum number of packets he can hold without tilting the plank? (Assume the weight of the plank acts through its centre.) A. 11 B. 12 C. 13 D. 18 E. 19 2001-CE-PHY 2 4 3
7. a Trolley F A student uses a friction-compensated runway to study Newton s second law of motion. The variation of the acceleration a of the trolley with the force F applied parallel to the runway is shown above. If the experiment is repeated with the runway making a larger angle of inclination with the horizontal, which of the following graphs (in dotted lines) represents the expected result? 0 F A. a B. a F 0 C. D. a a 0 F 0 F 0 F E. a 0 F 2001-CE-PHY 2 5 4 Go on to the next page
8. Force Time 0 The figure above shows the variation of the force acting on a car driver with time when the car hits a wall. The driver is not wearing a seat-belt. Which of the following graphs (in dotted lines) best shows the force acting on the driver if he is wearing a seat-belt? A. B. Force Force 0 Time 0 C. D. Time Force Force 0 Time 0 E. Force Time 0 Time 2001-CE-PHY 2 6 5
(For questions 9 and 10.) A man is pulling a suitcase along the horizontal ground as shown below. θ 9. Which of the following pairs of forces is/are action and reaction pair(s) according to Newton s third law of motion? (1) The gravitational force exerted by the earth on the man (2) The pulling force exerted by the man on the suitcase (3) The gravitational force exerted by the earth on the suitcase and The gravitational force exerted by the man on the earth and The friction exerted by the ground on the suitcase and The normal reaction exerted by the ground on the suitcase A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 10. If the rope is inclined at an angle θ to the horizontal and the tension in the rope is 100 N, find the work done by the man in pulling the suitcase for a distance of 5 m along the ground. A. 500 J B. 500 sinθ J C. 500 cosθ J D. 500 J sinθ E. 500 J cosθ 2001-CE-PHY 2 7 6 Go on to the next page
11. A rocket of mass 5000 kg is at rest in space. It then explodes and breaks into two parts P 1 and P 2 of mass 1000 kg and 4000 kg respectively. Find the ratio of the kinetic energy of P 1 to that of P 2. A. 1 : 1 B. 1 : 16 C. 1 : 64 D. 4 : 1 E. 16 : 1 12. The figure above shows a nail being driven into a wooden door with a hammer. Which of the following statements is/are correct? (1) Using a hammer can reduce the work done against the resistance on the nail by the door. (2) The force exerted by the nail on the door is larger than that exerted by the hammer on the nail. (3) The pressure exerted by the nail on the door is larger than that exerted by the hammer on the nail. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 8 7
13. Which of the following images in the photographs is/are virtual? (1) the image on the screen in a cinema (2) the image in a security mirror in a supermarket (3) the image on the surface of a pool of calm water A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 9 8 Go on to the next page
14. F Principal axis P Q R T S Two parallel rays from a distant object strike a concave mirror as shown above, where F is the focus. At which of the following points does the image of the object form? A. P B. Q C. R D. S E. T 2001-CE-PHY 2 10 9
15. An object is placed in front of a curved mirror and an image is formed as shown above. Which of the following describes the type of mirror being used and the nature of the image formed? Mirror Image A. convex real and formed in front of the mirror B. convex virtual and formed behind the mirror C. concave real and formed in front of the mirror D. concave real and formed behind the mirror E. concave virtual and formed behind the mirror 16. A melting ice block of mass 0.05 kg is mixed with x kg of water at 0 C in a well-insulated container. If 25 000 J of energy is supplied to the mixture, the mixture changes to water at 4 C. Find the value of x. (Given : specific latent heat of fusion of ice = 3.34 10 5 J kg 1, specific heat capacity of water = 4200 J kg 1 K 1.) A. 0.37 B. 0.44 C. 0.49 D. 1.44 E. 1.49 2001-CE-PHY 2 11 10 Go on to the next page
17. To power supply and joulemeter Thermometer Immersion heater Copper block Polystyrene plate The above apparatus is used to measure the specific heat capacity of a cylindrical copper block. The result of the experiment is as follows : Mass of copper block = m kg Initial temperature = 21 C Final temperature = 47 C Initial joulemeter reading = R 1 J Final joulemeter reading = R 2 J Which of the following expressions gives the specific heat capacity of copper (in J kg 1 K 1 )? A. 26 m(r 2 R 1 ) B. R1 R2 26 m C. D. E. R 2 R 1 26 m m( R 1 R2 ) 26 m( R 2 R1) 26 2001-CE-PHY 2 12 11
18. Temperature P Q 0 Time The figure above shows the cooling curve of a substance which is initially in the liquid state. The temperature of the substance remains unchanged during the period PQ. Which of the following statements about the substance during the period PQ is/are correct? (1) The substance is not losing any energy to the surroundings. (2) Latent heat is absorbed by the substance. (3) The average potential energy of the molecules of the substance is decreasing. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 19. A cup of liquid P and a cup of liquid Q of equal mass are heated at the same rate. It is found that the temperature of P is rising at a rate faster than that of Q. Which of the following deductions is/are correct? (1) P has a lower specific latent heat of vaporization than Q. (2) P has a lower boiling point than Q. (3) P has a lower specific heat capacity than Q. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 13 12 Go on to the next page
20. Stirrer Thermometer Rubber tubing Gas Flask Burner Bourdon gauge The above apparatus is used to study the relation between the pressure and temperature of a fixed mass of gas at constant volume. Which of the following can improve the accuracy of the experiment? (1) using a larger flask (2) using a shorter length of rubber tubing to connect the gauge and the flask (3) setting up a control experiment with the burner removed A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 14 13
21. V/m 3 Y X Z 0 T/K The above graph shows the V-T relation of a fixed mass of ideal gas. Point X denotes the initial state of the gas. The gas changes its state from X to Y, then from Y to Z and finally from Z back to X along the path shown. Which of the following statements about the pressure of the gas is/are correct? (1) The pressure remains unchanged in the transition from X to Y. (2) The pressure increases in the transition from Y to Z. (3) The pressure decreases in the transition from Z to X. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 22. Which of the following is not a transverse wave? A. radio waves B. visible light C. ultra-violet D. X-rays E. ultrasonic waves 2001-CE-PHY 2 15 14 Go on to the next page
23. R Direction of wave motion P Q S T Five corks are moving up and down on the surface of a pond as a water wave passes through them. At time t = 0, the positions of the corks are shown above. The figure below shows the displacement-time graph of one of the five corks. Which cork has the motion represented by the graph? (Note : Displacement is positive when the cork is above the still water surface.) Displacement 0 Time A. P B. Q C. R D. S E. T 24. A sonar on a ship is used to find the depth of the sea. An ultrasonic wave pulse is sent downwards from the ship towards the sea bed. The pulse travels with a speed of 1500 m s 1 in sea water. If the reflected pulse is received after 0.16 s, find the depth of the sea. A. 120 m B. 240 m C. 480 m D. 4688 m E. 9375 m 2001-CE-PHY 2 16 15
25. X Deep region Shallow region Y In the above diagram, XY represents a boundary between a deep region and a shallow region of water in a ripple tank. A series of straight water waves in the deep region travels towards XY. Which of the following diagrams best shows the wave pattern in the shallow region? A. B. X Y X Y C. D. X Y X Y E. X Y 2001-CE-PHY 2 17 16 Go on to the next page
26. d Obstacle Water waves of wavelength λ are diffracted as they pass through a gap of width d as shown above. Which of the following changes would produce the most significant diffraction effect? λ d A. remains unchanged halved B. remains unchanged doubled C. halved halved D. halved remains unchanged E. halved doubled 27. Which of the following relations is incorrect? A. 1 pascal (Pa) = 1 newton per metre squared (N m 2 ) B. 1 watt (W) = 1 joule per second (J s 1 ) C. 1 coulomb (C) = 1 ampere per second (A s 1 ) D. 1 volt (V) = 1 joule per coulomb (J C 1 ) E. 1 ohm (Ω) = 1 volt per ampere (V A 1 ) 2001-CE-PHY 2 18 17
28. A B Two charged spheres A and B are hanging at a point on a ceiling by two identical nylon threads. They remain at rest as shown above. Which of the following statements must be correct? (1) Both spheres carry positive charges. (2) The force acting on B by A is larger than the force acting on A by B. (3) The mass of A is larger than B. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 29. 2 Ω 1 Ω 3 Ω A If the ammeter in the above circuit reads 3 A, find the voltage of the battery. A. 11 V B. 12 V C. 13.5 V D. 15 V E. 18 V 2001-CE-PHY 2 19 18 Go on to the next page
30. A A 1 V A A 2 X S Y In the above circuit, the two resistors are identical. If switch S is closed, which of the following predictions is incorrect? A. The reading of the ammeter A 1 increases. B. The reading of the ammeter A 2 remains unchanged. C. The reading of the voltmeter remains unchanged. D. The power delivered by the battery increases. E. The potential difference between points X and Y increases. 31. Which of the following diagrams shows the correct connection of the fuse and switch of an electric kettle to the mains supply? (L : live, N : neutral, E : earth) A. B. L N E L N E C. D. L N E L N E E. L N E 2001-CE-PHY 2 20 19
32. Two electrical heaters X and Y are of ratings 110 V, 40 W and 110 V, 80 W respectively. Which of the following deductions about the two heaters is/are correct? (1) The operating resistance of X is twice that of Y. (2) X will consume a power of 80 W when it is connected to a 220 V mains supply. (3) Both heaters work at their rated values when they are connected in series to a 220 V mains supply. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 33. Y-gain Y-shift Y-gain Timebase Timebase Y-shift Figure (a) Figure (b) Figure (a) shows the trace of a signal on a CRO. In order to change the trace of the signal into the form shown in Figure (b), which of the following settings of the CRO should be adjusted? A. Y-gain only B. Y-shift only C. time base only D. Y-gain and Y-shift E. Y-gain and time base 2001-CE-PHY 2 21 20 Go on to the next page
34. 12 V A 12 V a.c. supply is connected to a transformer with turns ratio 1 : 1. The secondary coil is tapped at equal intervals as shown above. Two 6 V, 0.5 W light bulbs are connected to the secondary coil of the transformer. In which of the following cases will the two bulbs work at their rated values? (1) (2) (3) A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 22 21
35. Magnet CRO Y-input A long solenoid is placed in a vertical position and its two ends are connected to the Y-input of a CRO (with the time base switched on). A bar magnet is released above the solenoid so that it falls through the solenoid. Which of the following best represents the trace shown on the CRO? A. B. C. D. E. 2001-CE-PHY 2 23 22 Go on to the next page
36. Coil Soft-iron core 12 V The figure above shows an electromagnet which is used to pick up iron objects. Which of the following can increase the strength of the electromagnet? (1) increasing the number of turns of the coil (2) reducing the resistance of the variable resistor (3) replacing the battery with a 12 V a.c. power supply A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 37. P Q R S The above diagram shows a combination of two NAND gates. Which of the following sets of inputs would give a high output at S? (Take 1 for high voltage and 0 for low voltage.) P Q R (1) 1 1 1 (2) 1 0 0 (3) 0 0 0 A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1), (2) and (3) 2001-CE-PHY 2 24 23
38. 5 V Y X Z The figure above shows an incomplete circuit. A student uses a resistor, a switch and a light dependent resistor (LDR) to complete the circuit, so that the buzzer will sound only when the switch is pressed and the LDR is illuminated. Which of the following correctly shows the position of the three components? X Y Z 0 V A. switch LDR resistor B. resistor LDR switch C. resistor switch LDR D. LDR resistor switch E. LDR switch resistor 39. Radium ( 226 Ra) 88 decays by emitting an α particle to form a product nucleus X. Which of the following shows the correct equation for this decay? 226 222 88 86 A. Ra +α X 226 230 88 90 B. Ra +α X 226 88 224 84 C. Ra X + α 226 88 222 86 D. Ra X + α 226 88 226 89 E. Ra X + α 2001-CE-PHY 2 25 24 Go on to the next page
40. The initial activity of a radioactive isotope is 2000 disintegrations per second. After 4 hours, the activity of the isotope drops to 125 disintegrations per second. Find the half-life of the isotope. A. 15 minutes B. 30 minutes C. 48 minutes D. 60 minutes E. 80 minutes 41. α β β P Q R S The above shows part of a radioactive series. Which of the following nuclei are isotopes of the same element? A. P and Q B. P and R C. P and S D. Q and S E. Q, R and S 2001-CE-PHY 2 26 25
Directions : Each question below (questions 42 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 E according to the following table : 1st statement 2nd statement A. True True 2nd statement is a correct explanation of the 1st statement B. True True 2nd statement is not a correct explanation of the 1st statement C. True False D. False True E. False False 1st statement 2nd statement 42. The efficiency of using a screwjack to raise a car can be improved by increasing the length of the handle of the screwjack. 43. When a lens is used as a magnifying glass to look on a small object, the image formed is real. 44. The speed of gamma rays in air is much higher than that of visible light. 45. In examining foetuses (babies not yet born), ultrasonics are used but not X-rays. Increasing the length of the handle of the screwjack can reduce the effort required to raise the car. When a lens is used as a magnifying glass, the object and the image formed are on different sides of the lens. Gamma rays can pass through aluminium sheets of a few mm thick but visible light cannot. X-rays will cause damage to human cells whereas ultrasonics will not. END OF PAPER 2001-CE-PHY 2 27 26
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 1 s = ut + at 2 2 2 v = u + 2 as 2 (b) (c) (d) Potential energy gained by a body of mass m when raised through a height h is mgh. Kinetic energy of a body of mass m moving with speed v is 1 2 mv. 2 Power = force velocity (e) Equivalent resistance of two resistors R 1 and R 2 : (i) in series = R 1 + R 2 (ii) in parallel = R R R 1 2 + R 1 2 (f) Power = potential difference current 2001-CE-PHY 2 28 27
2001 Physics Paper 2 Question No. Key Question No. Key 1. B 26. A 2. C 27. C 3. B 28. B 4. E 29. A 5. A 30. E 6. B 31. D 7. C 32. A 8. C 33. D 9. A 34. E 10. C 35. A 11. D 36. C 12. B 37. E 13. D 38. D 14. B 39. D 15. E 40. D 16. B 41. C 17. C 42. D 18. B 43. E 19. B 44. D 20. C 45. A 21. E 22. E 23. B 24. A 25. A