(SAJC) 2024 H2 Phy Prelim P2 qn for sharing

1 SAJC Prelims 2024 9749/02 [Turn Over Class Index Number Name 23S ST. ANDREW’S JUNIOR COLLEGE JC 2 2024 Preliminary Examination _________________________________________________________________________ PHYSICS, Higher 2 9749/02 Paper 2 Structured Questions 28th August 2024 2 hours Candidates answer on the Question Paper. No Additional Materials are required. _________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name, index number and Civics Group 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. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 8 2 / 10 3 / 5 4 / 6 5 / 7 6 /11 7 / 11 8 / 22 Total / 80

2 SAJC Prelims 2024 9749/02 [Turn Over This document consists of 22 printed pages including this page. Data speed of light in free space c = 3.00 x 108 m s-1 permeability of free space μo = 4 π x 10-7 H m-1 permittivity of free space εo = 8.85 x 10-12 F m-1 = (1/(36π)) x 10-9 F m-1 elementary charge e = 1.60 x 10-19 C the Planck constant h = 6.63 x 10-34 J s unified atomic mass constant u = 1.66 x 10-27 kg rest mass of electron me = 9.11 x 10-31 kg rest mass of proton mp = 1.67 x 10-27 kg molar gas constant R = 8.31 J K-1 mol-1 the Avogadro constant NA = 6.02 x 1023 mol-1 the Boltzmann constant k = 1.38 x 10-23 J K-1 gravitational constant G = 6.67 x 10-11 N m2 kg-2 acceleration of free fall g = 9.81 m s-2 Formulae uniformly accelerated motion s = u t + ½ a t2 v2 = u2 + 2 a s work done on/by a gas W = p ΔV hydrostatic pressure p = ρ g h gravitational potential φ = temperature T / K = T / oC + 273.15 pressure of an ideal gas p = 1 3 𝑁𝑚 𝑉 〈𝑐2〉 mean translational kinetic energy of an ideal gas molecule E = kT displacement of particle in s.h.m. x = xo sin ω t velocity of particle in s.h.m. v = v0 cos ω t v = ± ω electric current I = Anvq resistors in series R = R1 + R2 + ... resistors in parallel 1 / R = 1 / R1 + 1 / R2 + ... electric potential V = alternating current/voltage x = xo sin ω t magnetic flux density due to a long straight wire B = 𝜇0𝐼 2𝜋𝑑 magnetic flux density due to a flat circular coil B = 𝜇0𝑁𝐼 2𝑟 magnetic flux density due to a long solenoid B = 𝜇0𝑛𝐼 radioactive decay x = xo exp (-λ t)

3 SAJC Prelims 2024 9749/02 [Turn Over decay constant λ = Answer all the questions in the space provided. 1 A car has a total mass of 1100 kg and an initial speed 18.0 m s-1. A set of traffic lights turn red when the driver is some distance from them. The driver applies a braking force on the car. Fig. 1.1 is the graph of braking force against time for the car approaching the traffic lights. Fig. 1.1 (a) (i) Calculate the speed of the car at 10 s. speed = …………………………….. m s-1 [2] (ii) State an assumption made in your calculations above. ……………………..…………………………………………………...……………… …...……….…………………….………………………………………………….. [1]

4 SAJC Prelims 2024 9749/02 [Turn Over (b) On Fig. 1.2, sketch a graph to show how the speed of the car changes from the instant the braking force is applied till the force becomes zero. [3] Fig. 1.2 (c) On Fig. 1.3, sketch a graph to show how the distance travelled by the car from the instant the braking force is applied till the force becomes zero. [2] Fig 1.3 distance

5 SAJC Prelims 2024 9749/02 [Turn Over 2 (a) State the principle of conservation of momentum. ………………………………..………………………………………………...………………. ……………………………..…………………………………………………...………………. ………………….…………………….…………………………………………………..… [2] (b) A firework is initially stationary. It explodes into three fragments A, B and C that move in a horizontal plane, as shown in the view from above in Fig. 2.1. Fig. 2.1 Fragment A has a mass of 3m and moves away from the explosion at a speed of 4.0 m s–1. Fragment B has a mass of 2m and moves away from the explosion at a speed of 6.0 m s−1 at right angles to the direction of A. Fragment C has a mass of m and moves away from the explosion at a speed v and at an angle θ as shown in Fig. 2.1. Calculate: (i) the angle θ,

6 SAJC Prelims 2024 9749/02 [Turn Over θ = …………………………... ° [3] (ii) the speed v. v = …………………………... m s-1 [2] (c) The firework in (b) contains a chemical that has mass 5.0 g and has chemical energy per unit mass 700 J kg −1. When the firework explodes, all the chemical energy is transferred to the kinetic energy of fragments A, B and C. Calculate the mass m. m = …………………………... kg [3]

7 SAJC Prelims 2024 9749/02 [Turn Over 3 A sphere of radius 2.1 mm falls with terminal velocity through a liquid, as shown in Fig. 3.1. Fig. 3.1 Three forces act on the moving sphere. The weight, W, of the sphere is 7.2 × 10 –4 N and the upthrust, U, acting, on it is 4.8 × 10 –4 N. The viscous force, FV, acting on the sphere is given by FV = krv where r is the radius of the sphere, v is its velocity and k is a constant. The value of k is 17 kg m-1 s–1. (a) Calculate the density ρ of the liquid. ρ = .............................................. kg m–3 [2] (b) (i) On the sphere in Fig. 3.1, draw three arrows to show the weight, the upthrust and the viscous force. Label these arrows W, U and FV respectively. [1] (ii) Determine the magnitude of the terminal velocity of the sphere. terminal velocity

8 SAJC Prelims 2024 9749/02 [Turn Over velocity = ................................................ m s–1 [2] 4 (a) The planet Mars has a mass of 6.4 x 10 23 kg and a diameter of 6.8 x 103 km. A rock, initially at rest a long distance from Mars, travels towards its surface. Assuming that Mars is isolated in space, show that the speed of the rock as it reaches the surface of Mars is 5.0 x 103 m s-1. [2] (b) (i) Helium-4 may be assumed to be an ideal gas. Calculate the temperature of helium -4 gas at which the r.m.s. speed of its atoms is equal to the speed of the rock in (a). [2] (ii) Suggest, with a reason, whether helium-4 is found on the surface of Mars. ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………………………. ……………………………………………………………………………………… [2]

9 SAJC Prelims 2024 9749/02 [Turn Over 5 (a) A progressive wave transfers energy. A stationary wave does not transfer energy. State two other differences between progressive waves and stationary waves. 1. ……………………………………………………………………………………..………… ………………………………………………………………………………………………..… 2. ………………………………………………………………………………………..………. ……………………………………………………………………………………………….. [2] (b) A stationary wave is formed on a stretched string between two fixed points A and B. The variation of displacement y of the particles of the string wit