CJC.H2.PRELIM.2023.P2.QP

CANDIDATE NAME CLASS 2T PHYSICS 9749/2 Paper 2: Structured Questions August 2023 2 hours Candidates answer on the Question Paper. No Additional Materials are required. 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 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. This document consists of 22 printed pages. [Turn over FOR EXAMINER’S USE Q1 / 10 Q2 / 10 Q3 / 8 Q4 / 10 Q5 / 14 Q6 / 9 Q7 / 19 PAPER 2 / 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 Answer all the questions in the spaces provided. 1 (a) A swimmer is swimming at a constant speed in a pool. Drag forces due to the water oppose the motion of the swimmer. Explain why the swimmer travels at constant speed. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. ………………………………………………………………………………………………………….. …...…………………………………………………………………………………………....……..[2] (b) The power output P of a swimmer used to overcome the drag forces travelling when at speed v is given by 3 D 1P= C ρAv2 where CD is the drag coefficient, ρ is the density of water and A is the frontal area of the swimmer. In an experiment to measure the C D for freestyle, the data for a particular swimmer is collected. The data is shown in Table 1.1. Table 1.1 quantity magnitude uncertainty P/ W 294 ± 2 ρ/ kg m-3 1000 ± 1 A/ m2 0.20 ± 0.01 v/ m s-1 1.4 ± 0.1 Determine the C D of the swimmer, with its actual uncertainty. Give your answer to an appropriate number of significant figures. C D = ………………. ± ……..…… [4]

5 (c) (i) Derive, from the definition of power, an expression of the drag force F experienced by the swimmer in terms of the velocity v. [2] (ii) Hence or otherwise, calculate the work done by the swimmer to overcome the drag force when he swims a distance of 50 m at a constant speed of 1.4 m s-1. work done = ………………. J [2] [Total: 10] [Turn over

6 2 (a) Fig. 2.1 shows a mass initially travelling at right angles to the Earth’s uniform gravitational field. Fig. 2.1 Describe the subsequent motion of the mass. ………………………………………………………………………..………………………………… ………………………………………………………………………….…………………………… [1] (b) Fig. 2.2 shows an electron initially travelling parallel to a uniform electric field. Fig. 2.2 Describe the subsequent motion of the electron. ………………………………………………………………………..………………………………… ………………………………………………………………………..………………………………… ………………………………………………………………………….……………………………[2]

7 (c) Fig. 2.3 shows a long molecule placed in a uniform electric field. Fig. 2.3 The ends of the molecule have equal but opposite charges. Describe and explain the initial motion of the molecule in the electric field. ……………………………………………………………………………………………………..…… ……………………………………………………………………………………………………..…… ……………………………………………………………………………………………………..…… …………………………………………………………………………………………………….. [2] (d) Fig. 2.4 shows a sphere of weight 1.6 × 10-2 N with an electric charge of +2.0 μC. It is released from rest, in vacuum, between two parallel, vertical metal plates. The separation of the plates is 0.10 m. One plate has a potential of +80 V and the other plate has a potential of -80 V. Fig. 2.4 (i) Determine the electric force experienced by the sphere. force = ……………… N [2] [Turn over +2.0 μC 0.10 m +80 V -80 V

8 (ii) On Fig. 2.4, sketch the path taken by the sphere after it is released. [1] (e) The variations with separation of the gravitational potential energy UG and of the electric potential energy UE between two protons are shown in Fig. 2.5. Fig. 2.5 Explain why the gravitational potential energy and the electric potential energy have opposite signs. ……………………………………………………………………………………………………..…… ……………………………………………………………………………………………………..…… ……………………………………………………………………………………………………..…… …………………………………………………………………………………………………….. [2] [Total: 10] UG UE

9 3 A cantilever spar cable -stayed bridge is a unique yet functional variation of the traditional cable suspension bridge. In one such model bridge, a bridge beam is supported by a cable. The cable connected at an angle of 30° to a non-uniform cantilever spar of length L slanted at an angle of 50° from the ground with a base at P , as shown in Fig. 3.1. Fig 3.1 (not to scale) The tension in the cable is 1000 N and the weight of the cantilever spar is 2330 N. (a) By taking moments about P , show that the centre of mass of the cantilever spar is located at a distance of 0.33L from P. [3] (b) Calculate the magnitude of the force acting on the cantilever spar at P. magnitude of force at P = ………………… N [3] [Turn over

10 (c) The traditional cable-stayed bridge design is shown in Fig 3.2 Fig 3.2 Suggest, with a reason, one advantage a cantilever spar cable-stayed bridge may have over a traditional cable-stayed bridge design. ……………….………………………………………………………………..................................... ……………….………………………………………………………………..................................... ……………….