TJC 2022 Prelim P3

TEMASEK JUNIOR COLLEGE 2022 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER PHYSICS 9749/03 Paper 3 Longer Structured Questions 13 September 2022 2 hours Candidates answer on the Question Paper. No additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, CG and subject tutor’s name on all the work you hand in. 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. Section A Answer all questions. Section B Answer one question only You are advised to spend one and a half hour 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. For Examiner’s Use 1 2 3 4 5 6 7 8 s.f. Total This document consists of 21 printed pages and 3 blank pages.

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 2 TJC 2022 Paper 3 (2 hours) Data speed of light in free space c = 3.00 x 108 m s-1 permeability of free space o = 4 x 10-7 H m-1 permittivity of free space o = 8.85 x 10-12 F m-1 or (1/(36)) x 10-9 F m-1 elementary charge e = 1.60 x 10-19 C the Planck constant h = 6.63 x 10-34 Js 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 = ut + ½ at2 v2 = u2 + 2as work done on/by a gas W = p ΔV hydrostatic pressure p = gh gravitational potential  = –Gm/r temperature T/K = T/oC + 273.15 pressure of an ideal gas p = 3 1 V Nm < c2 > mean translational kinetic energy of an ideal gas molecule E = 2 3 kT displacement of particle in s.h.m. x = xosint velocity of particle in s.h.m. v = vocost = )( 22 xxo − electric current I = Anvq resistors in series R = R1 + R2 + .... resistors in parallel 1/R = 1/R1 + 1/R2 + .... electric potential V = rε4π Q o alternating current/voltage x = xo sint 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 = onI radioactive decay x = x0 exp(−t) decay constant λ = 𝑙𝑛2 𝑡1/2

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 3 [Turn over Section A Answer all the questions in this Section in the spaces provided. 1 (a) A monoatomic ideal gas A is contained in an insulated cylinder to prevent the loss of heat, while monoatomic ideal gas B is contained in a cylinder without any insulation, as shown in Fig. 1.1. Fig. 1.1 Initially, the two gases have the same volume of 2.90  10−4 m3, the same pressure of 1.05  105 Pa and the same temperature of 303 K. (i) Explain what is meant by the internal energy of an ideal gas. [1] (ii) Determine the number of molecules in gas A. number of molecules = [2] gas A insulation gas B

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 4 (iii) Determine the mean translational kinetic energy of a molecule of gas A. mean translational kinetic energy = J [1] (b) When gas A is compressed to a volume of 2.10  10−4 m3, its temperature rises to 357 K. Gas B is compressed very slowly to the same volume of 2.10  10−4 m3. (i) Determine the change in internal energy of gas A during the compression. change in internal energy = J [2] (ii) Determine the work done on gas A during the compression. work done on the gas = J [1] (iii) On Fig. 1.2, sketch the variation with volume of the pressure of gas A and gas B. Include appropriate labels, and values of pressure and volume. [3] Fig.1.2 pressure / 105 Pa volume / 10−4 m3

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 5 [Turn over 2 Fig. 2.1 shows a mass m attached to a spring performing simple harmonic motion in the vertical y direction. The spring constant k of the spring is 61.4 N m-1. Fig. 2.1 At y = 0.000 m, the lowest point of the oscillation, the gravitational potential energy of the system is defined as 0 J. As the system oscillates, its total energy is a constant and comprising kinetic energy, elastic potential energy and gravitational potent ial energy. At different positions y above the lowest position of oscillation, the kinetic energy and the elastic potential energy of the system vary as shown in Fig. 2.2. energy / J Fig. 2.2 y lowest position y = 0.000 m gravitational potential energy = 0 J m vertical position y / m kinetic energy elastic potential energy

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 6 (a) Define simple harmonic motion. [2] (b) Determine the total energy of the system. Show your working clearly. total energy = J [2] (c) Sketch on Fig. 2.2 a graph showing the variation with y of the gravitational potential energy of the system. [2] (d) Hence or otherwise, show that mass m is 0.250 kg. m = kg [2] (e) Find the period T of the oscillation. T = s [2]

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 7 [Turn over 3 Fig. 3.1 shows two large, vertical parallel plates, A and B, with plate B being connected to earth. An electron was emitted perpendicularly from plate A with an initial velocity v of 4.30 x 10 6 m s−1. The electron experiences an electric force of 1.12 x 10−16 N towards plate A in the region between the two plates. Fig. 3.1 (a) Calculate the potential of plate A. potential of plate A = V [2] (b) (i) The electron comes to a stop momentarily at a point P. Use your answer in (a) to determine the potential at P. potential at P = V [2] (ii) On Fig. 3.1, draw the equipotential line passing through P. [2] A 10.0 cm electron v B

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 8 (c) Another electron of the same speed is now ejected from plate A towards plate B at an angle less than 90o to plate A. State, with a reason, whether the electron will stop before, at or beyond the equipotential line passing through P. [2] (d) A proton is projected with a velocity of 3.5  106 m s-1 along the axis midway between two parallel plates of length 20 cm as shown in Fig. 3.2. The uniform electric field between the plates has an intensity of 2.0  104 N C-1 and is directed upward. Fig. 3.2 (i) Determine the position where the proton will strike plate P. proton will strike P at cm from point of entry [3] Diagram not to scale 0.50 cm 20 cm proton 3.5  106 m s-1 plate P plate Q

DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9 [Turn over (ii) An alpha particle that enters the electric field at the same point and with the same velocity as the proton. Describe and explain with some calculations whether the alpha particle will hit or exit the plates.