CJC.H2.PRELIM.2023.P3.QP

1 CANDIDATE NAME CLASS 2T PHYSICS 9749/3 Paper 3: Longer Structured Questions September 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name and class 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. Write on the cover page the question number attempted in Section B. You are advised to spend one and a half hours on Section A and half an hour on Section B. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 26 printed pages and 0 blank page. [Turn over FOR EXAMINER’S USE SECTION A Q1 / 8 Q2 / 8 Q3 / 8 Q4 / 14 Q5 / 8 Q6 / 11 Q7 / 3 SECTION B / 20 TOTAL /80 Catholic Junior College JC2 Preliminary Examinations Higher 2

2 DATA speed of light in free space c = 3.00 x 108 m s-1 permeability of free space µ0 = 4π x 10-7 H m-1 permittivity of free space ε0 = 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 mol-1 gravitational constant G = 6.67 x 10-11 N m2 kg-2 acceleration of free fall g = 9.81 m s-2

3 FORMULAE uniformly accelerated motion s = u t + ½ a t2 v2 = u2 + 2as work done on / by a gas W = p ∆V hydrostatic pressure p = ρgh gravitational potential φ = - Gm r temperature T / K = T / ˚C + 273.15 pressure of an ideal gas p = 1 3 Nm V 〈c2〉 mean translational kinetic energy of an ideal gas molecule E = 3 2 kT displacement of particle in s.h.m. x = x0 sin ωt velocity of particle in s.h.m. v = v0 cos ωt = 22 0 x x− ±ω electric current I = Anvq resistors in series R = R1 + R2 + ... resistors in parallel 1/R = 1/R1 + 1/R2 + ... electric potential V = Q 4πεor alternating current / voltage x = x0 sin ωt magnetic flux density due to a long straight wire B = μoI 2πd magnetic flux density due to a flat circular coil B = μoNI 2r magnetic flux density due to a long solenoid B = μonI radioactive decay x = x0 exp(-λt) decay constant λ = 1 2 ln2 t [Turn over

4 Section A Answer all questions in this section in the spaces provided. 1 A ball of mass 10 g is dropped from a height and falls through air. The variation with time t of the speed of the ball v is shown in Fig. 1.1 Fig 1.1 (a) (i) Use Fig 1.1. to determine the acceleration of the ball at time t = 0. Show your construction on Fig 1.1. acceleration = ……………………. m s-2 [3] (ii) By reference to your answer in (a)(i), suggest the difference, if any, between your answer and the acceleration of free fall. …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... ……………………………………...……………………………………………………….. [2]

5 (b) Calculate the maximum resistive force acting on the ball. force = …..…………………… N [1] (c) On Fig 1.1, draw another curve to show the variation with time t of the speed of the ball v if the ball was dropped in a more viscous medium. [2] [Total: 8] [Turn over

6 2 A binary star consists of two stars A and B. The two stars may be considered to be isolated in space. The centres of the two stars are separated by a constant distance, as illustrated in Fig. 2.1. Fig. 2.1 Star A of mass M A has a larger mass than star B of mass MB such that MA = 4MB. The stars are in circular orbits about each other such that the centre of their orbits is at a fixed point O. The radius of orbit of star A and star B are Ar and Br respectively. The period of each orbit is T. (a) Explain why the two stars must always be directly opposite as they move in the circular orbit. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………. [2] (b) Show that 4B A r r = . Explain your working. [2] star A mass MA star B mass MB O

7 (c) If the period T is 104 days and the separation of the centres of the stars is 111.1 10× m, (i) calculate the angular velocity of star A, and angular velocity = …………………………………. rad s -1 [1] (ii) determine the mass of each star. mass M A of star A = …………………………………. kg mass MB of star B = …………………………………. kg [3] [Total:8] [Turn over

8 3 Ice is less dense than liquid water due to the structure of the bonds between the molecules when it is in a solid state. Hence, when ice melts into water at 0°C, the density of water increases. As the liquid water increases in temperature, its density further increases to a maximum value at 4.0°C. (a) Consider a 5.0 kg block of ice at 0°C that is melted into liquid water at the same temperature using a heat source supplying a constant power of 4180 W. (i) The specific latent heat of fusion of ice is 3.34 x 105 J kg-1. Determine the time taken to completely melt the block of ice into liquid water at 0°C. time = ……………….. s [3] (ii) The density of ice at 0°C is 0.915 kg m-3 while the density of liquid water at 0°C is 0.999 kg m-3. Calculate the work done on the ice by a constant atmospheric pressure of 1.01 x 105 Pa as the ice melts completely into water at 0°C. work done on the ice = ………………. J [3]

9 (b) The first law of thermodynamics for a system can be expressed as ΔU = q+w where ΔU is the increase in internal energy of the system, q is the heat supplied to the system and w is the work done on the system. Use the words positive, negative and zero to complete Table 3.1 for the three terms in the equation for each of the processes shown. You may use each word once, more than once, or not at all. Table 3.1 Process ΔU q w Ice melting into liquid water at 0°C Liquid water warming up from 0°C to 4°C [2] [Total: 8] [Turn over

10 4 (a) State what is meant by radioactive decay. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… …………………………………………………………………………………………….. [2] (b) A radiation detector is placed close to a radioactive source. The detector does not surround the source. Radiation is emitted in all directions and, as a result, the activity of the source and the measured count rate are different. Suggest two other reasons why the activity and the measured count rate may be different. 1. …………………………………………………………………