NJC 2025 H2 Physics Prelim P3SectionB QP

[Turn over NATIONAL JUNIOR COLLEGE SENIOR HIGH 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER PHYSICS Paper 3 Longer Structured Questions (Section B) Candidate answers on the Question Paper. 9749/03 19 Sep 2025 2 hours No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your subject class, registration number and name 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 a 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 B Answer one questions only. 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. For Examiner’s Use Section B 7 / 20 8 / 20 H

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4 Answer one question from this Section in the spaces provided. 7 (a) A cylindrical tube, containing some sand, floats upright in a liquid of density 𝜌, as shown in Fig. 7.1. Fig. 7.1 The tube has cross-sectional area A. The total mass of the tube and sand is M. The tube floats in equilibrium with its base a distance h below the surface of the liquid. (i) By considering the pressure due to a fluid, show that 𝑀 = 𝜌ℎ𝐴. Explain your working. [2] (ii) The tube is now held stationary below the equilibrium floating position of the tube. Show that, when released, the acceleration a of the tube is related to its displacement x from the equilibrium position by the equation: 𝑎 = − (𝜌𝐴𝑔 𝑀 ) 𝑥 where g is the acceleration of free fall. Explain your working.

5 [Turn over [3] (iii) Explain whether the tube is performing simple harmonic motion. ………………………………………………………………………………………………… …… ………………………………………………………………………………………………… …… ………………………………………………………………………………………………… …… ………………………………………………………………………………………………… … [2] (iv) The mass M of the tube and sand is 130 g. The area of cross -section A of the tube is 5.3 cm2. The tube, floating in a liquid of density 1.2 × 10 3 kg m−3, is held stationary 1.3 cm below its equilibrium position and then released. Calculate 1. the frequency of oscillation of the tube, frequency = ……………………………… Hz [3] 2. the total energy of oscillation of the tube. energy = ……………………………… J [2]

6 (b) A dipper oscillates at a frequency of 2.0 Hz in a ripple tank. Surface water waves ripple circularly out from the dipper with wavelength 1.0 cm as shown in Fig. 7.3. Fig. 7.3 (i) Explain why the amplitude of the wave decreases with distance from the dipper. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… …………………………………………………………………………………………………… [2] (ii) Show that the dipper and the water at a point 2.0 cm away from the dipper oscillate in phase. [2] wavefronts dipper

7 [Turn over (iii) At a particular instance in time, the dipper is at its maximum negative displacement. X on Fig. 7.4 shows the variation with distance of the amplitude of the water wave. Fig. 7.4 On Fig. 7.4, sketch the displacement-distance graph of the water wave at this instance. [2] (iv) The dipper is at its maximum negative displacement when time = 0 s. On Fig. 7.5, sketch the displacement-time graph of the water at a point 3.0 cm away from the dipper. displacement / mm distance / cm X

8 Fig. 7.5 [2] [Total: 20] 8 (a) The masses of various nuclides and of various sub-atomic particles, are shown in Fig. 8.1. nuclide or sub- atomic particles proton number mass / u electron n/a 0.000549 proton n/a 1.007276 neutron n/a 1.008664 helium-4 2 4.002603 thallium-205 81 204.974428 bismuth-209 83 208.980399 polonium-209 84 208.982430 Fig. 8.1 (i) Bismuth-209 is radioactive. Use the data in Fig. 8.1 to determine which type(s) of radiation ( 𝛼 or 𝛽) it is possible for bismuth-209 to emit. Explain your reasoning. displacement / mm time / s

9 [Turn over radiation emitted: ……………………………………………………………………………… [4] (ii) Determine the binding energy per nucleon of bismuth-209. binding energy per nucleon = ……………………………… MeV [4] (b) A radiation detector is placed close to a radioactive source. The variation with time t of the measured count rate is shown in Fig. 8.2.

10 Fig. 8.2 (i) State the feature of Fig. 8.2 that indicates the random nature of radioactive decay. ………………………………………………………………………………………………… …… …………………………………………………………………………………………………… [1] (ii) State the background count rate recorded by the radiation detector. background count rate = ……………………………… min–1 [1] (iii) Use Fig. 8.2 to determine the half-life of the radioactive isotope in the source. half-life = ……………………………… hours [3]