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1 CCC Hoh Fuk Tong College Mock Examination 2009 – 2010 Physics Paper II Secondary : 7 Time allowed : 3 hours ( 1:45 p.m. - 4:45 p.m.) Name : ______________________________ Date : 3 / 3 / 2010 Marks : 93 Class : S. 7S Number : ______ Section A : Answer ALL questions. Section B : Answer Any THREE questions. Instructions for Section A 1. You should use an HB pencil to mark all your answers on the Answer Sheet. Wrong marks must be completely erased. 2. You should mark only ONE answer for each question in Section A. If you mark more than one answer, you will receive NO MARKS for that question. 3. No marks will be deducted for wrong answers in Section A. Section A There are 45 questions in this section. Each question is followed by four suggested answers. Where necessary, take the acceleration due to gravity to be 10 m s -2 and take the speed of light in air to be 3 x 108 m s-1. 1. Q 30o R P X A uniform metre rule of mass 0.2 kg is hinged to a wall at P and the other end R is connected by a wire attached to the wall at Q, vertically above P as shown in the diagram above. A block X of mass 0.1 kg is hung from the rule 25 cm from R. The metre rule is horizontal. Find the tension in the wire. A. 1.5 N B. 3.5 N C. 4.0 N 2 D. 7.0 N 2. A particle of mass m, traveling at speed u, strikes a stationary particle of mass 2m. As a result, the particle of mass m is deflected through 60o and has a final speed of u/2. The speed of the particle of mass 2m after this collision will be A. u/4 B. u/2 C. (0.433) u D. (0.217) u 3. A small ball is projected from A with 3 ms-1 at 30 with horizontal. The ball hits the wall at B that is at the same horizontal level as A. Calculate the distance AB. A A. B. C. D. 4. 0.45 m 0.78 m 0.90 m 1.80 m A particle X moving with kinetic energy E and momentum p makes a head-on collision with an identical particle Y which is initially at rest. Two particles stick together after collision. Which of the following correctly represents the kinetic energy and momentum of X after the collision? A. B. C. D. 5. B 30 kinetic energy 0 E/2 E/4 E/4 momentum p p/2 p/2 p/4 An object of mass 8.0 kg is tied to one end of a string and whirled around in a vertical circle of radius 2.0 m. At the top of the circular path, the speed of the object is found to be 5.0 ms-1. The tension of the string at this position is A. B. C. D. 0N 20 N 100 N 180 N 3 D 6. H E C I A B G F J ABCDEFGHIJ is a smooth metal rail bent in such a way that BCDE and FGHI are two circles of radii 1.2 m and 0.8 m respectively. A, B, F and J are on the same horizontal level. A small marble is projected at A so that the reaction force acting on the marble at D is zero. Which of the following statements is INCORRECT ? A. B. C. D. 7. The centripetal force on the marble at D equals to its weight. The centripetal force on the marble at D is smaller than that at B. The centripetal force on the marble at F is greater than that at B. The marble will loss contact with the rail somewhere between G and H. Satellite A is observed to revolve the earth once in 2 days, while another satellite B takes 128 days. The ratio of the radius of orbit taken by A to that by B is A. 1 : 64 B. 1 : 32 C. 1 : 16 D. 1 : 8 8. A body is in simple harmonic motion of amplitude 0.50 m and period 4π seconds. What is the speed of the body when the displacement of the body is 0.30 m? A. B. C. D. 0.10 ms-1 0.15 ms-1 0.20 ms-1 0.40 ms-1 9. The objective lens of an astronomical telescope has a diameter 30 mm and focal length 0.5 m. The eyepiece has a focal length of 0.1 m and the instrument is in normal adjustment. The diameter of the eye-ring is A. B. C. D. 7.5 mm 6 mm 4 mm 2 mm 4 10. A diffraction grating, used at normal incidence, gives a green line of wavelength 5.4 x 10-7 m in a certain order superimposed on the violet line of wavelength 4.05 x 10-7 m of the next order. If the angle of diffraction is 30o, the number of lines per meter in the grating is A. B. C. D. 11. 1.8 x 105 3.09 x 105 4.26 x 105 1.35 x 106 Stationary waves are set up on a length of rope fixed at both ends. Which one of the following statements is correct ? A. B. C. D. Between adjacent nodes, particles of the rope vibrate in phase with each other. The mid point of the rope is always stationary. Nodes need not necessarily be present at each end of the rope. Particles of the rope at adjacent antinodes always move in the same direction. 12. Coherent monochromatic light of wavelength emerges from the slits X and Y to form dark fringes at P, Q, R and S in a double slit apparatus. Which one of the following statements is correct ? A. B. C. D. When the distance D is increased, the separation of the fringes decreases. When the distance between X and Y is increased, the separation of the fringes decreases. When the width of the slit T is decreased, the separation of the fringes decreases. 1 There is a dark fringe at P because (YP – XP) is 2 . 2 5 13. In a progressive sound wave, the displacement y of air molecules from their mean position varies with the distance x from O as shown above. The displacement towards the right is taken as positive. Which of the following statements is / are correct ? (1) (2) (3) Compression is at Q. Particle at P is moving to the right. Particle at R is moving to the right. A. B. C. D. (1) only (3) only (1) and (2) only (2) and (3) only 14. A capacitor of capacitance 10 F is fully charged through a resistor R to a p.d. of 20 V using the circuit shown. Which one of the following statements is INCORRECT ? A. B. C. D. The p.d. across the capacitor is 20 V. The p.d. across the resistor is 0 V. The energy stored by the capacitor is 2 mJ. The total energy taken from the battery during the charging process is 2 mJ. 6 15. P 30 1.2A Q S R A square coil PQRS, of 20 turns and length 0.15 m, is placed in a uniform magnetic field of 0.4 T. The magnetic field is parallel to the plane of the coil. The side PQ makes 30 with the magnetic field. The current in the coil is 1.2 A. Calculate the magnetic force acting on PQ and QR of the coil. A. B. C. D. Force on PQ 0.72 N 0.72 N 1.25 N 1.25 N Force on QR 0.72 N 1.25 N 0.72 N 1.25 N 16. 4 p.d. / V 2 10 10 resistor lamp 0 0.2 Current / A 0.4 3.0 V The graph above shows the relationship between potential difference and current for a particular filament lamp and a fixed 10 resistor. What is the current in the circuit shown above? A. B. C. D. 0.10 A 0.20 A 0.30 A 0.35 A 7 17. C R A S After the switch S is closed, the variable resistor R is reduced at a rate that the charging current remains constant at 20 A for a time of 30 s. During this time, the p.d. across the capacitor rises from 0 V to 12 V. What is the capacitance of the capacitor? A. B. C. D. 8 F 20 F 50 F 200 F 18. X Z uniform magnetic field Y The diagram shows a square coil with its plane parallel to a uniform magnetic field. Which one of the following would induce an e.m.f. in the coil? A. B. C. D. movement of the coil to the left movement of the coil downwards rotation of the coil about an axis through XY rotation of the coil about an axis perpendicular to the plane of the coil through Z 19. The second overtones of an open pipe X and a closed pipe Y have the same frequency at a given temperature. The ratio of length of X to that of Y is A. 3 : 5 B. 5 : 3 8 C. 6 : 5 D. 5 : 6 20. A battery, a resistor and a parallel plate capacitor are connected in series. If the plates of the capacitor shown in the diagram are brought closer together. Which of the following quantities will increase in magnitude ? (1) The charges on both plates. (2) The field between the plates. (3) The potential differences across the plates. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 21. The rotating coil of a motor has a resistance of 1 . When it is powered by a supply of e.m.f. 24 V and negligible internal resistance, the current through the coil is 4 A. What is the maximum useful output power delivered by the motor ? A. 16 W B. 32 W C. 64 W D. 80 W 22. A sound source approaches an observer with a uniform acceleration towards the observer. Which of the following statements is/are true ? (1) The pitch heard by the observer is higher than that of the source. (2) The pitch heard is increasing gradually, (3) The initial pitch heard depends on the initial distance between the source and the observer. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 23. A radio produce a sound intensity level of 50 dB at a point 2 m away from it. If the power output of the radio is halved, what is the sound intensity level at a point 4 m from the radio ? ( You may regard the radio as a point source ) 9 A. 12.5 dB B. 41.0 dB C. 49.4 dB D. 56.0 dB 24. 2 Hz beats are obtained when a flute and a 512 Hz tuning fork are sounded. When the fork is doubled, the beat frequency becomes 4 Hz. What note(s) could the flute have been playing ? A. 510 Hz B. 514 Hz C. 508 Hz or 516 Hz D. 510 Hz or 514 Hz 25. The work function of a piece of metal is and the maximum kinetic energy of the photoelectrons is emitted when a light shines on it. Which of the following can increase the maximum kinetic energy of the emitted photoelectrons ? (1) Increase the intensity of light (2) Increase the frequency of light (3) Replace the metal with a lower work function. A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only 26. A mass M on a spring oscillates along a vertical line with the same period T as an object O in uniform circular motion in a vertical plane. When M is at its highest point, O is at its lowest point. What is the least time interval between successive instants when the acceleration of M is exactly in the opposite direction to the acceleration of O? A. B. C. D. T 4 T 2 3T 4 T 10 27. A L-shaped block ABC of weight 30 N rests on a horizontal ground. The centre of mass of the block is at G. A horizontal force P is applied at point A. When P reaches 20 N, the block overturns. 12 cm P A G 15 cm B C 30 N If the force P is applied in the opposite direction, what is its least value in order to overturn the block? A. B. C. D. 4N 16 N 24 N 32 N 28. A satellite is in orbit at a height h above the surface of a planet of mass M and radius R. What is the velocity of the satellite? A. B. C. D. GM ( R h) R GM ( R h) R GM ( R h) GM ( R h) 29. Medium 1 Medium 2 11 The above wavefront diagram shows some waves passing through two different media. Which of the following is /are possible conclusion(s) ? Nature of wave Medium 1 Medium 2 (1) light waves air glass (2) sound waves water air (3) water waves shallow water deep water A. B. C. D. (1) only (1) and (2) only (2) and (3) only (1), (2) and (3) 30. y S1 RS Q P t 0 S2 (i) (ii) In a ripple tank, S1 and S2 are two coherent sources vibrating in the same phase. Figure (i) shows the wave pattern at time t=0. The solid lines represent the crests of the water waves. Figure (ii) shows the displacement-time graph of water particle at P. What are the PQ displacement-time graphs for particle at R and S where PR and 4 PQ PS ? 2 12 y-t graph at R A. y-t graph at S y y t 0 B. t t t 0 t y y 0 0 y y 0 D. t y y 0 C. 0 t 0 t 31. Sound waves are emitted from a stationary source. When an observer is moving towards the source, which of the following quantities increases? (1) (2) (3) The frequency of the sound waves detected by the observer. The wavelength of the sound waves. The speed of the sound waves. A. B. C. D. (1) only (2) only (1) and (3) only (2) and (3) only 32. 4 k 15 V 1 k 220 F 10 V In steady state, which of the following statements is / are correct? 13 (1) The current passing through the 4 k resistor is 1 mA. (2) The potential difference across the capacitor is 11 V. (3) The charges stored in the capacitor 20 C. A. B. C. D. (1) only (1) and (2) only (2) and (3) only (1), (2) and (3) 33. A capacitor of capacitance 15 F is fully charged and the potential difference across its plates is 8.0 V. It is then connected into the circuit as shown. The switch S is closed at time t = 0. Which one of the following statements is correct? A. B. C. D. The time constant of the circuit is 6.0 ms. The initial charge on the capacitor is 12 C. After a time equal to twice the time constant, the charge remaining on the capacitor is Q0e2, where Q0 is the charge at time t = 0. After a time equal to the time constant, the potential difference across the capacitor is 2.9 V. 34. Y A X B P Q Two long solenoids, X and Y, placed coaxially as shown above. The data about the solenoids are listed below: radius turn density current Solenoid X 5 cm 1200 m-1 1.0 A (clockwise viewed from B) Solenoid Y 3 cm 2400 m-1 0.5 A (anticlockwise viewed from B) 14 Point P is on the common axis and Point Q is 4 cm from the axis. The permeability of the air is 4 10 Hm . Which of the following statements is / are correct ? -7 -1 (1) The magnetic field at P is zero. (2) The magnetic field at Q is 1.5 mT. (3) The magnetic field at Q points to the left. A. B. C. D. (1) only. (1) and (2) only (2) and (3) only (1), (2) and (3) 35. A circular coil of 200 turns and radius 4 cm is fixed in a uniform magnetic field which is perpendicular to the plane of the coil. The coil’s total resistance is 10 . The flux density of the field is increased at a uniform rate of 0.5 T s -1 in the first 5 s. It is then kept constant for another 5 s. uniform magnetic field Which of the following graphs correctly show the variation of the current I induced in the coil from time t = 0 to t = 10 s. A. B. I/mA I/mA 5 5 0 5 10 0 t/s C. 5 10 t/s 5 10 t/s D. I/mA I/mA 50 0 50 5 10 t/s 0 15 36. An a.c. circuit has a total impedance of 13 and a total reactance of 5 . What is the average power dissipated in the circuit when the r.m.s. current passing through it is 2 A ? A. B. C. D. 4W 20 W 48 W 52 W 37. C R V A capacitor C and a resistor R is connected in series with an a.c. supply V. VC and VR denote the phasors of the p.d. across the capacitor and that across the resistor respectively. Which of the following phasor diagrams is correct? A. B. VR VC VC C. VR D. VR VC VC 38. VR p / kPa B 200 A C 100 0 V / m3 0.2 0.4 16 A fixed mass of an ideal gas undergoes the process ABC as shown in the pressure-volume diagram. process? What is the work done on the gas during the 1 x 104 J 3 x 104 J –1 x 104 J –3 x 104 J A. B. C. D. 39. P/105 Pa 8 6 4 2 V/m3 0 2 4 6 8 10 12 14 The pressure P of a fixed mass of ideal gas changes with its volume V as shown above. Which of the following graphs shows the corresponding pressure-temperature (P-T) relationship? A. B. P/105 Pa P/105 Pa 8 8 6 4 2 6 4 2 T 0 C. T 0 D. P/105 Pa P/105 Pa 8 8 6 4 2 0 T 6 4 2 0 40. Which of the following equations is / are based on the principle of conservation of energy ? T 17 1 mv2 2 (2) U = Q + W 1 (3) p + v2 + gh = constant 2 (1) hf = W + A. B. C. D. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 41. The apparatus shown in the diagram is designed to accelerate alpha particles. An alpha particle travelling at a speed of 2.60 × 106 ms−1 passes through a hole in plate A. The mass of an alpha particle is 6.64 × 10−27 kg and its charge is 3.2 × 10−19C. The e.m.f. of the power supply is 2.5 x 104 V and has negligible internal resistance. Calculate the kinetic energy of the alpha particle when it reaches plate B. A. B. C. D. 8.00 × 10-15 J 1.52 × 10-14 J 2.24 × 10-14 J 3.04 × 10−14 J. 42. In Rutherford experiment, one alpha particle, of kinetic energy 7.7 MeV, is bombarding towards a distant gold nucleus. The alpha particle is deflected as shown. Calculate the kinetic energy of the alpha particle at P where is 6.5 x 10-14 m from the gold nucleus. (Given: charge of an electron = 1.6 x10-19 C; permittivity of vacuum = 8.85 x 10-12 F m-1; atomic number of gold = 79; atomic number of alpha particle = 2.) 18 P Alpha particle Gold nucleus A. B. C. D. 3.5 MeV 4.2 MeV 7.3 MeV 11.2 MeV 43. If monochromatic light of wavelength 420 nm is incident on a metal plate, electron will be emitted. The work function of the metal is 3.4 x 10-19 J. Which of the followin g are the possible of the kinetic energy of the emitting electrons. (Given: Planck constant = 6.6 x10-34 Js; mass of an electron = 1.6 x 10-19 C) (1) 0.41 eV (2) 0.82 eV (3) 1.64 eV A. B. C. D. (1) only (1) and (2) only (2) and (3) only (1), (2) and (3) 44. n=4 n=3 -1.6 eV -2.7 eV n=2 -5.5 eV n=1 -10.4 eV The figure shows the possible energy levels of a mercury atom. A free electron with kinetic energy 8.4 eV collides with a mercury atom, which is in its ground state. The change in kinetic energy of the mercury atom in the collision may be neglected. What is/are the possible value(s) for the kinetic energy of the electron after collision ? 19 (1) (2) (3) 0.7 eV 2.9 eV 3.5 eV A. B. C. D. (1) only (2) only (1) and (3) only (2) and (3) only 45. ln A Y X 0 T 2T t The activity A of a radioactive sources X and Y are measured at different time. Graphs of ln A against time t for X and Y are shown above. Which of the following statements is/are correct ? (1) The initial activity of source X and Y are equal. (2) The half life of Y is twice that of X. (3) At t = 0, the number of active nuclides of Y is twice that of X. A. B. C. D. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) END OF SECTION A Section B Answer any THREE questions for this Section. Write your answers in the ANSWER BOOK provided. Where necessary, take the acceleration due to gravity to be 10 m s-2 and take the speed of light in air to be 3 x 108 m s-1. 20 1. a. b. i. ii. State Newton’s law of universal gravitation. ( 1 mark ) What is meant by the term ‘weightlessness’ ? Astronauts inside a space shuttle orbiting around the Earth usually appear to be weightless. Give a brief explanation of this with the help of suitable force diagrams. iii. State another situation in which one can experience ( 5 marks ) weightlessness. c. Suppose that a satellite with mass m is orbiting around the Earth at a distance r from its centre. The mass and the radius of the Earth are respectively M and R i. Explain why the orbit of the satellite must lie at the equator plane of the Earth. ii. Deduce mathematically the expressions for the potential energy, the kinetic energy and the total energy of the satellite. iii.By using the result in (c)(ii), sketch, on the same graph, the variation of the potential energy, the kinetic energy and the total energy of the satellite with its distance from the Earth starting from r = R to r = . iv. What would happen to the motion of the satellite when ( 10 marks ) it is subject to air resistance ? Explain briefly. 2. a. What is the principle of superposition? Use this principle to explain the formation of antinodes and nodes in the stationary wave. What are beats and describe briefly how they are produced? Briefly describe how the measurement of beats would be used to detect the speed of cars in a police radar speed check system. With the aid of a diagram, explain qualitatively why different colours are observed on a soap bubble under sunlight. Explain why Polaroid sunglass can effectively reduce the glare of the sun reflecting from the sea. b. c. d. 3. a. i. ii. b. (5 marks) (5 marks) (3 marks) (3 marks) Describe and explain briefly the methods adopted in a steady magnetic field using a Hall probe. an alternating magnetic field using a search coil. Compare the different physical mechanisms in these ( 11 marks ) two methods and derive any necessary mathematical expressions. Comment briefly on the main factors that might affect the accuracy of the measurements. ( 5 marks ) 21 4. a. A B R i. ii. b. By considering a unit charge moving round the above circuit, distinguish between the electromotive force (e.m.f.) of the battery and the potential difference (p.d.) across its terminals A and B. Explain why, in general, the p.d. across the terminals of the battery is lower than its e.m.f. The resistor R is about 10 k. Draw a circuit diagram to show how a moving-coil milliammeter and a voltmeter should be connected in the circuit in order to measure the resistance R. Explain whether the value R calculated from the readings of the milliammeter and voltmeter would be greater or smaller than its actual ( 6 marks ) value. Consider a fixed mass of an ideal gas contained in a cubical box. Show that, from first principles, the pressure p of the gas is proportional to the mean square speed c 2 of the gas molecules. State the major ( 10 marks ) assumption(s) you have made. *** END OF PAPER *** 22