NJC H2 Physics Prelim P2 QP

[Turn over NATIONAL JUNIOR COLLEGE SENIOR HIGH 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER PHYSICS Paper 2 Structured Questions Candidate answers on the Question Paper. No Additional Materials are required. 9749/02 24 August 2023 2 hours READ THE INSTRUCTION FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a 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. Answers all questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 10 2 / 10 3 / 8 4 / 6 5 / 6 6 / 10 7 / 10 8 / 20 Total (80m) This document contains 24 printed pages and 3 blank page.

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4 1 A sphere is projected horizontally. The sphere is photographed at intervals of 0.10 s. The images of the sphere are shown against a grid in Fig. 1.1. Air resistance is negligible. (a) Use data from Fig.1.1 to determine the acceleration of free fall. acceleration = ……………. m s-2 [2] (b) Explain how your choice of the data point from Fig 1.1 helps to improve the reliability of your calculation in (a). …………………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………... [2] Fig. 1.1

5 [Turn over (c) Determine the speed of the sphere 1.2 s after release. speed = ………………. m s-1 [4] (d) On the grid, draw the path of the sphere assuming air resistance is not negligible. [2] [Total: 10]

6 2 (a) A prototype space shuttle attached to a rocket stands vertically on its launching pad. The total mass of the spaceship and rocket (inclusive of the mass of a man in it and its fuel) is 8.5 × 104 kg. On ignition, gas is ejected from the rocket at a speed of 6.0 × 103 m s–1 relative to the rocket, and the fuel is consumed at a constant rate of 138 kg s–1. Calculate (i) the thrust on the rocket. thrust = ……………………….. N [1] (ii) the initial weight of the rocket. weight = ……………………….. N [1] (iii) the time it takes for the fuel to burn before the rocket leaves the launching pad. time = ………………………… s [2] (iv) the acceleration of the rocket after the fuel is consumed for 200 s. acceleration = ………………………… m s–2 [2]

7 [Turn over (b) Body A of mass 2.0 kg moves towards Body B of 3.0 kg as illustrated in Fig. 2.1. Fig. 2.1 (i) Explain why it is not possible for both bodies to stop at the same instant. ………………………………………………………………………………………………………. ………………………………………………………………………………………………… [1] (ii) Fig. 2.2 is a velocity -time sketch graph showing how the velocity of each body varies. The interaction between the bodies is elastic. Label the graph to show 1. which curve is for body A, [1] 2. the times at which each body stops, [1] 3. the time at which they are at their distance of closest approach. [1] [Total: 10] Body A v Body B v velocity v u r v e A v u r v e A 0 time Fig. 2.2

8 3 (a) Explain the origin of upthrust. …………………………………………………………………………………………………………………………. …………………………………………………………………………………………………………………... [1] (b) A buoy is attached to a rope which is anchored to the seabed. Currents in the sea cause the buoy to be displaced so that the rope makes an angle of 25 ° with the vertical, as shown in Fig. 3.1. The buoy is in equilibrium. Fig. 3.1 The currents in the sea exert a horizontal force of 140 N on the buoy and the weight of the buoy is 130 N. (i) Sketch the forces acting on the buoy in Fig. 3.2. Fig. 3.2 [2] 25° seabed buoy surface of the sea direction of current rope

9 [Turn over (ii) Show that the upthrust acting on the buoy is 430 N. [2] (iii) Determine the percentage of the volume of the buoy that is submerged in the sea. The density of sea water is 1000 kg m-3 and density of the buoy is 230 kg m-3. percentage of volume of buoy submerged ＝....................................... % [3] [Total: 8]

10 4 A rocket is midway between the Earth and Moon as shown in Fig. 4.1. Fig. 4.1 The distance between the centers of mass of the Moon and Earth is 384 × 103 km. The mass of the Moon is 7.35 × 1022 kg and the mass of the Earth is 5.97 × 1024 kg. (a) Calculate the escape velocity of the rocket when it is midway between the Earth and Moon. escape speed ＝....................................... m s-1 [3] (b) Explain qualitatively how the escape velocity of the rocket will change as its position is moved nearer the moon from its current position. ……..……………………………………………………………………………………………………….. ……..……………………………………………………………………………………………………….. ……..……………………………………………………………………………………………………….. ……..……………………………………………………………………………………………………….. ……..……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. [3] [Total: 6] Moon Earth rocket