2021 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 26 August 2021 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 or graphs. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Answer all 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 / 11 3 / 10 4 / 9 5 / 11 6 / 12 7 / 20 Total / 80

2 Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use 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 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use Formulae uniformly accelerated motion, s = ut + at 2 v 2 = u 2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p =  g h gravitational potential,  =  temperature T / K = T / oC + 273.15 pressure of an ideal gas p = mean translational kinetic energy of of an ideal gas molecule, E =  displacement of particle in s.h.m., x = xo sin t velocity of particle in s.h.m., v = vo cos t =  electric current I = A n v q resistors in series, R = R1 + R2 +  resistors in parallel, 1/R = 1/R1 + 1/R2 +  electric potential, V = alternating current/voltage, x = xo sin t magnetic flux density due to a long straight wire B = magnetic flux density due to a flat circular coil B = magnetic flux density due to a long solenoid B = radioactive decay, x = xo exp(t) decay constant,  = 12 t ln2 2 1 r Gm 21 3 Nm cV  3 2 kT  22 xxo  r Q o4 2 o d   I 2 oN r  I on I

4 Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use Answer all the questions in the spaces provided. 1 The speed v of a transverse wave on a uniform string is given by the expression Tv m l where T is the tension of the string, l is its length and m is its mass. An experiment is conducted to determine the speed v of the wave. The measurements are shown in Table 1.1. Table 1.1 quantity measurement uncertainty T 1.8 N 0.1 N l 126 cm 2 cm m 5.1 g 0.2 g (a) (i) Using the data in Table 1.1, determine the percentage uncertainty in the calculation of the speed v of the transverse wave. percentage uncertainty = ………………………… % [2] (ii) Using your answer in (a)(i) and the data in Table 1.1, determine the value of v, with its absolute uncertainty, to an appropriate number of significant figures. v = ……………………  …………………… m s–1 [2]

5 [Turn over Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (b) Another student used a different set-up to determine the value of v. His values of v are as follows: 20.6 m s–1, 21.1 m s–1, 20.4 m s–1 (i) With reference to the value of v obtained in (a)(ii), comment on the accuracy of the values of v that the second student obtained. …………………………………………………….………………….…………….. ………………………………………………..…………………………………. [1] (ii) State the type of error that is present in the measurements obtained by the second student. Suggest a possible way to minimise or eliminate the error. ………………..…………..…...………...………………………….………………. ………………...………………………...……….…………………………………. ……..………………………..…………....…………………………..………… [2]

6 Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use 2 A ball is kicked from horizontal ground towards a vertical wall as shown in Fig. 2.1. Fig 2.1 (not to scale) The horizontal distance between the initial position of the ball and the base of the wall is 24 m. The ball is kicked with an initial velocity v at an angle of 28 to the horizontal. The ball just hits the top of the wall after a time of 1.5 s. (a) Calculate the horizontal component vX of the velocity of the ball. vX = ………………………… m s–1 [1] (b) Hence or otherwise, show that the initial vertical component vY of the velocity of the ball is 8.5 m s–1. [1]

7 [Turn over Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (c) The ball is kicked at time t = 0. Assume that the vertical component vY of the velocity of the ball is positive in the upwards direction. (i) On Fig. 2.2, sketch the variation with time t of vY for the time until the ball hits the wall. Fig. 2.2 [3] (ii) Using Fig. 2.2, determine the maximum height above the ground that the ball reached. maximum height = ………………………… m [2] (iii) Hence or otherwise, determine the ratio of its kinetic energy gravitational potential energy when the ball is at its maximum height. ratio = ………………………… [2]

8 Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (iv) If air resistance is not negligible, on Fig 2.2, sketch the variation with time t of vY for the time until the ball hits the ground. Label this line W . [2] 3 (a) Define upthrust. ……………………………………..……………………………………………………. ……………………………………..……………………………………………………. .…………………………………..…………………………………………………... [2] (b) A mass M with a wire attached to it is fully submerged in water as shown in Fig. 3.1. Mass M is 950 kg with a base area of 0.40 m2 and a height of 0.50 m. Fig. 3.1 Given that the density of water is 1000 kg m−3, show that the tension in the wire is 7360 N. [2] M

9 [Turn over Anglo-Chinese Junior College 2021 J2 H2 9749 Paper 2 Preliminary Examination For Examiner’s Use (c) Mass M is actually being held up by a crane made of a uniform rigid beam AB hinged to the ground at A, and held in place by two wires CD and BE, as shown in Fig. 3.2. Fig. 3.2 The beam AB has a length of 3.00 m and a mass of 80.0 kg. D is the midpoint of rod AB.