MI 23M1PrelimQP (H2 PHYSICS P3)

Class Adm No Candidate Name: This document consists of 24 printed pages. [Turn over 2023 Preliminary Examination Pre-University 3 H2 PHYSICS 9749/03 Paper 3 Longer Structured Questions 19 September Candidates answer on the Question Paper. 2 hours No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Do not turn over this page until you are told to do so. Write your full name, class and Adm number 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. You are advised to spend one and 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 Sect A 1 / 10 2 / 12 3 / 12 4 / 12 5 / 14 Sect B 6 / 20 7 / 20 Presentation Total /80

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4 Section A Answer all the questions in the spaces provided. 1 An object A of mass 9.0 kg and object B of mass 1.0 kg travel towards each other along a smooth horizontal surface in a straight line and collide head-on. The initial speeds of object A and B before the collision are u and 3u respectively. In Fig. 1.1, the variation with time t of momentum p is shown from t = 0 to 3.0 s for particle A and from t = 0 to 1.0 s for particle B. Fig. 1.1 9.0u p 0 1.0 t / s 2.0 –3.0u 3.0

5 [Turn over (a) (i) Momentum is conserved when two objects collide or interact. State the condition under which momentum is conserved. ……………………………………………………………………………………………………... [1] (ii) On Fig. 1.1, draw the variation with t of p from 1.0 s to 3.0 s for object B. [2] (iii) Explain how the principle of conservation of momentum is used to complete the graph in (a)(ii). ……………………………………………………………………………………………………... …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. [1] (b) Explain, with appropriate working, whether the collision between objects A and B is elastic. ……………………………………………………………………………………………………............... …………………………………………………………………………………………….………………... [3] (c) (i) Show that the magnitude of the force acting on object A during the collision is 7.2u. [1] (ii) Explain how the graphs in Fig. 1.1 are consistent with Newton’s third law of motion during the collision. ……………………………………………………………………………………………………... …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. ……………………………………………………………………………………………………... …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. [2] [Total: 10]

6 2 (a) The kinetic theory of gases is based on a number of assumptions about the molecules of a gas. State the assumption that is related to the volume of the molecules of the gas. …………………………………………………………………………………………………………….... ………………………………………………………………………………………… ….………………... [1] (b) An ideal gas occupies a volume of 950 cm 3 at a pressure of 2.10 × 10 5 Pa and a temperature of 280K. Each molecule has a diameter of approximately 3 × 10 –10 m. Estimate the total volume of the gas molecules. volume = ……………………………m3 [3] (c) With reference to your answer in (b), suggest why the assumption in (a) is justified. …………………………………………………………………………………………………………….... …………………………………………………………………………………………….………………... [1] (d) The ideal gas undergoes the cycle of changes PQRP as shown in Fig. 2.1.

7 [Turn over Fig. 2.1 Some energy changes during one complete cycle of PQRP are shown in Table. 2.1. change P → Q change Q → R change R → P thermal energy transferred to gas / J work done on gas / J increase in internal energy of gas / J +97.0 ........................ ........................ 0 –42.5 ........................ ........................ ........................ ........................ Table. 2.1 (i) State the total change in internal energy of the gas during one complete cycle PQRP. Explain your answer. ……………………………………………………………………………………………………… …………………………………………………………………………………………….……….. ……………………………………………………………………………………………………… [2] (ii) Complete Table 2.1 to show the energy changes for the gas. Show your working clearly in the space below. [5] [Total: 12]

8 3 A small wooden block (cuboid) of mass m floats in water, as shown in Fig. 3.1. Fig. 3.1 The top face of the block is horizontal and has area A. The density of the water is . (a) State the names of the two forces acting on the block when it is stationary. …………………………………………………………………………………………….………………... [1] (b) The block is now displaced downwards as shown in Fig. 3.2 so that the surface of the water is higher up the block. Fig. 3.2 State and explain the direction of the resultant force acting on the wooden block in this position. …………………………………………………………………………………………….………………... …………………………………………………………………………………………….………………... [1] (c) The block in (b) is now released so that it oscillates vertically. The resultant force F acting on the block is given by F = –Agρx where g is the gravitational field strength and x is the vertical displacement of the block from the equilibrium position. (i) Explain why the oscillations of the block are simple harmonic. …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. wooden block mass m water of density new position of water surface original position of water surface

9 [Turn over …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. [2] (ii) Show that the angular frequency  of the oscillations is given by 𝜔 = √𝐴𝜌𝑔 𝑚 [2] (d) The block is now placed in a liquid with a greater viscosity. The block is displaced and released so that it oscillates vertically. The variation with displacement x of the acceleration a of the block is measured for the first half oscillation, as shown in Fig. 3.3. Fig. 3.3 (i) Explain why the maximum negative displacement of the block is not equal to its maximum positive displacement. …………………………………………………………………………………………….………..

10 …………………………………………………………………………………………….……….. …………………………………………………………………………………………….……….. [1] (ii) Use Fig. 3.3 to determine the frequency of the block. frequency = ...................................... Hz [2] (iii) The mass of the block is 0.57 kg. Use Fig. 3.3 to determine the decrease E in energy of the oscillation for the first half oscillation. E = ............................................... J [3] [Total: 12]