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 dipp