ACJC 2025 J2 H2 Physics Prelim P2

This paper consists of 26 printed pages Anglo-Chinese Junior College Physics Preliminary Examination Higher 2 CANDIDATE NAME CLASS CENTRE NUMBER S 3 0 0 4 INDEX NUMBER PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9749/02 28 August 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Answer all the questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiners’ use only 1 / 7 2 / 7 3 / 5 4 / 11 5 / 10 6 / 9 7 / 11 8 / 20 Total / 80

2 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination DATA AND FORMULAE Data speed of light in free space, c = 3.00  108 m s−1 permeability of free space, o = 4  10−7 H m−1 permittivity of free space, o = 8.85  10−12 F m–1 (1/(36))  10–9 F m–1 elementary charge, e = 1.60  10−19 C the Planck constant, h = 6.63  10−34 J s unified atomic mass constant, u = 1.66  10−27 kg rest mass of electron, me = 9.11  10−31 kg rest mass of proton, mp = 1.67  10−27 kg molar gas constant, R = 8.31 J K−1 mol−1 the Avogadro constant, NA = 6.02  1023 mol−1 the Boltzmann constant, k = 1.38  10−23 J K−1 gravitational constant, G = 6.67  10−11 N m2 kg−2 acceleration of free fall, g = 9.81 m s−2

3 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination Formulae uniformly accelerated motion, s = 21 2ut at+ v 2 = u 2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p =  g h gravitational potential,  = − Gm r temperature T/K = T/oC + 273.15 pressure of an ideal gas p = 21 3 Nm cV mean translational kinetic energy of an ideal gas molecule, E = 3 2 kT displacement of particle in s.h.m., x = xo sin t velocity of particle in s.h.m., v = vo cos t =   22 oxx − electric current I = Anvq resistors in series, R = R1 + R2 +  resistors in parallel, 1/R = 1/R1 + 1/R2 +  electric potential, V = 4 o Q r alternating current/voltage, x = xo sin t magnetic flux density due to a long straight wire B = 0 2 d   I magnetic flux density due to a flat circular coil B = 0 2 N r  I magnetic flux density due to a long solenoid B = 0n I radioactive decay, x = xo exp(−t) decay constant,  = 12 ln2 t

4 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use Answer all the questions in the spaces provided. 1 A rigid bar of mass 450 g is held horizontally by two supports A and B, as shown in Fig. 1.1. Fig. 1.1 Support A is 45 cm from the centre of gravity C of the bar and support B is 25 cm from C. A ball of mass 140 g falls vertically onto the bar such that it hits the bar at point D, which is 50 cm from C, as shown in Fig. 1.1. The variation with time t of the velocity v of the ball before, during and after hitting the bar is shown in Fig. 1.2. Fig. 1.2

5 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (a) For the time that the ball is in contact with the bar, use Fig. 1.2 to determine (i) the change in momentum of the ball, change in momentum = …………...……… N s [2] (ii) the magnitude of the force exerted by the ball on the bar. force = …………...……… N [3] (b) Hence, for the time that the ball is in contact with the bar, calculate the magnitude of the force exerted on the bar by support A. force = …………...……… N [2] [Total: 7]

6 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use 2 A plane is flying with a velocity v of 1220 m s − at an angle of 30 with respect to the horizontal, as shown in Fig. 2.1. Fig. 2.1 At an altitude of x, a crate is released from the plane. The crate hits the target on the ground after 16.8 s. Assume air resistance is negligible. (a) (i) Calculate the value of x. x = …………………… m [2] (ii) Determine the speed attained by the crate just before it hits the target. speed = …………………… 1m s− [3]

7 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (iii) On Fig. 2.2, sketch the variation with time t of the horizontal velocity vx of the crate. Label this graph S. Fig. 2.2 [1] (b) If air resistance is not negligible, on Fig. 2.2, sketch the variation with t of vx. Label this graph R. [1] [Total: 7] 0 vx / t / s 0

8 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use 3 A student, aspiring to be an astrophysicist is contemplating about the possibility of building a spacecraft that can house astronauts for a prolonged period. Fig. 3.1 shows the spacecraft rotating in space. The spacecraft has a ring structure and uses its own rotation to create an artificial gravity that is similar to Earth for the inhabitants. Fig. 3.1 (a) Fig. 3.2 shows the cross section of the spacecraft and how the astronaut is positioned. Fig. 3.2 On Fig. 3.2, draw arrow(s) to represent the force(s) acting on the astronaut. [1]

9 [Turn over Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (b) The astronaut in the spacecraft has a constant speed of 1100 m s − . (i) Explain why the astronaut experiences a resultant force. ….……………………………………………………………………………………. ….……………………………………………………………………………………. ….……………………………………………………………………………………. ………………………………………………………………………………….… [2] (ii) Determine the radius of the spacecraft so that the resultant force experienced by the astronaut is equal to his weight on Earth. radius = …………………… m [2] [Total: 5]

10 Anglo-Chinese Junior College 2025 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use 4 (a) State what is meant by a polarised wave. ……………………………………………….……….…………………………………… ……………………………………………….……….…………………………………… ………………………………………………………….……………………………… [1] (b) Two sheets of polaroid P and Q are placed close to each other. Their directions of polarisation are parallel to each other, as shown in Fig. 4.1. Fig. 4.1 A monochromatic beam of unpolarised light is incident on polaroid P. The beam after pa