(ACJC) 2024 J2 H2 Physics Prelim P3

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 3 Longer Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9749/03 28 August 2024 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. Section A Answer all questions. Section B Answer one question only. You are advised to spend one and a half hours on Section A and half an hour on Section B. 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 Section A 1 / 10 2 / 12 3 / 12 4 / 14 5 / 12 Total / 60 Section B 6 / 7 / 20 Grand Total / 80

2 Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 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 2024 J2 H2 9749 Paper 3 Preliminary Examination Formulae uniformly accelerated motion, s = ut + 2 1 at 2 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 c V  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 = 2 o d   magnetic flux density due to a flat circular coil B = 2 oN r  magnetic flux density due to a long solenoid B = on radioactive decay, x = xo exp(−t) decay constant,  = 12 ln2 t

4 Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use Section A Answer all the questions in this Section in the spaces provided. 1 (a) (i) Define linear momentum. ………………………………………………………………………………...……… …………………………………………………………………………………..... [1] (ii) State the principle of conservation of momentum. ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………...……… …………………………………………………………………………………..... [2] (b) Fig. 1.1 shows two spheres, A and B, with identical sizes but of different masses, connected by a light elastic string. Fig. 1.1 The masses of A and B are 2.0 kg and 1.0 kg respectively. The two spheres are initially held at rest 0.90 m apart on a smooth horizontal surface with the string in tension. They are then simultaneously released. The string releases 12 J of energy as it contracts to its natural length. (i) Determine the speeds acquired by each of the spheres. speed of A = ……………………… m s−1 speed of B = ……………………… m s−1 [4] A B string

5 [Turn over Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use (ii) Determine the distance of the position of A from its initial position when the two spheres collide. distance = ……………………… m [3] [Total: 10]

6 Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use 2 A fixed mass of monatomic ideal gas is being studied for its thermodynamic properties. (a) State what is meant by an ideal gas. ………………………….……….………………………………………………..…..…... ……………………………….….………………………………………………..…..…... …………………………….……….……………………………………………..…..…... …….……………………………………...………………………..………………..… [2] (b) The gas is initially placed in a container of volume 2.3  104 cm3 and at a pressure of 4.8  105 Pa. The temperature of the gas is 65 C. (i) Determine the number of atoms in the gas. number = ……………………… [2] (ii) Determine the internal energy of this gas at 65 C. internal energy = ……………………… J [2]

7 [Turn over Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use (iii) The temperature is then increased to 75 C. Determine the ratio of o o root-mean-square (r.m.s.) speed of the gas molecules at 65 C root-mean-square (r.m.s.) speed of the gas molecules at 75 C . ratio = ……………………… [2] (c) The gas then undergoes a cycle of processes ABC as shown in Fig. 2.1. Fig. 2.1 During the isobaric process A→B, the gas expands from 2.3  104 cm3 to 6.3  104 cm3 at a constant pressure of 4.8  105 Pa. During the isothermal process B→C, the gas contracts from 6.3  104 cm3 to 2.3  104 cm3 and the pressure increases to 13.1  105 Pa. During the isovolumetric process C→A, the gas reduces in pressure to 4.8  105 Pa.

8 Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use (i) Explain why process B→C is isothermal. …………………………………………………………………………………….. ……………………………………………………………………………….... [1] (ii) Complete Table 2.1. Show your working. Table 2.1 process work done on the gas /  104 J heat supplied to the gas /  104 J increase in internal energy /  104 J A → B B → C 3.05 0 C → A −2.88 [3] [Total: 12]

9 [Turn over Anglo-Chinese Junior College 2024 J2 H2 9749 Paper 3 Preliminary Examination For Examiner’s Use 3 A cylindrical tube, containing some sand, floats upright in a liquid of density  with its base at a depth of h below the liquid surface as shown in Fig. 3.1. Fig. 3.1 The tube has a cross-sectional A and the total mass of the tube and the sand is M. (a) By considering forces acting on the tube, explain why the tube is able to float. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. ……………………………………………………………………………………...….. [2]

10 Anglo-Chinese Junior College