2024 CHS Sec 4 Physics Prelim Paper 2

Name: Index Number: Class: CATHOLIC HIGH SCHOOL Preliminary Examination Secondary 4 (O-Level Programme) PHYSICS 6091/02 Paper 2 Structured and Free Response 23 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black link. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. Candidates are reminded that all quantitative answers should include appropriate units. The use of an approved scientific calculator is expected, where appropriate. Candidates are advised to show all their working in a clear and orderly manner, as more marks are awarded for sound use of Physics than for correct answers. The number of marks is given in brackets [ ] at the end of each question or part question. For examiner’s use only: Section A / 70 Section B / 10 Total / 80 Overall Marks % Paper 1 40 30% Paper 2A 70 50% Paper 2B 10 Paper 3 40 20% This document consists of 23 printed pages. 70  s.f.  formula Paper 2A

2 Section A Answer all the questions in this section. 1 A ball is thrown vertically upwards from ground level. Air resistance is not negligible. The variation with time t of the velocity v of the ball is shown in Fig. 1.1. Fig. 1.1

3 (a) (i) Describe the motion of the ball from t = 0 s to t = 1.75 s. [2] (ii) Explain, in terms of forces acting, why the ball moves as described in (a)(i). [3] (b) State the time where the gradient of the graph is equal to the magnitude of the acceleration of free fall. time = [1] (c) The ball falls back to ground level at t = 3. 50 s without reaching terminal velocity. Sketch, on Fig. 1.1, the variation of the velocity of the ball with time from t = 1.75 s to t = 3.50 s. [2]

4 2 Fig. 2.1 shows an electric motor and pulley wheel being used to raise a load M. The electric motor uses a belt to turn the pulley wheel. Fig. 2.1 (a) When the electric motor lifts the load, it transfers energy. Describe the energy transfers between the electric motor, the load M and the surrounding air. Assume there are no energy transfers to the belt and pulley wheel. [3]

5 (b) Fig. 2.2 shows the force on the pulley from the load M. Fig. 2.2 The weight of load M is 2.5 N and the weight acts at a distance of 20 cm from the pivot of the pulley wheel. Calculate the moment of the weight of load M about the pivot. moment = [2] (c) Fig. 2.3 shows the dimensions of load M. The load is removed from the pulley and dropped into a tank containing an unknown liquid. It is completely submerged in the liquid and remains stationary with the same orientation shown in Fig. 2.3 without touching the base of the tank. The gravitational field strength g is 10 N / kg. Fig. 2.3 (not to scale) Show that the density of the unknown liquid is 3 500 kg / m3. [2]

6 3 A cylinder that contains a fixed amount of a gas is shown in Fig. 3.1. Fig. 3.1 The cylinder is fitted with a piston that moves freely. (a) Explain how the molecules of the gas produce a pressure on the piston. [2] (b) The gas in the cylinder is heated. Explain, using ideas about molecules, why a downward force needs to be applied on the piston to keep the volume of the gas constant. [2] (c) An engineer using the cylinder wants to minimise heat transfer from the gas to the surrounding air. Suggest why: (i) the piston is made of wood, [1] (ii) the piston has a seal around it, which prevents the movement of air into and gas out of the cylinder, [1] gas

7 (iii) the outer walls of the cylinder are silver in colour. [1]

8 4 A loudspeaker emits a sound wave, which is a longitudinal wave. The variation of the air pressure with distance from the loudspeaker at a particular time is shown in Fig. 4.1. Fig. 4.1 (not to scale) (a) State what is meant by a longitudinal wave. [1] (b) On Fig. 4.1, (i) draw a line with arrows to indicate the wavelength of the wave, and label this line as W, (ii) mark a point to show a centre of rarefaction, and label this point as R, (iii) mark a point where the air molecules are at the maximum displacement from their rest positions, and label this point as M. [3] (c) A student is standing at point A which is at a distance of one wavelength from the loudspeaker. He moves to point B which is at a distance of two wavelengths from the loudspeaker. He claims that as he moves from A to B , the frequency of the sound wave decreases. State and explain whether the claim is correct. [2]

9 (d) The speed of the sound wave is 330 m / s. The wavelength of the sound wave is 3.3 m. Sketch, on Fig. 4.1, the variation of the air pressure with distance from the loudspeaker after 15 ms. Show all relevant workings below. [2]

10 5 Fig. 5.1 illustrates three ways in which different electromagnetic waves may be used to send television signals into a home. Fig. 5.1 In a satellite television, electromagnetic waves travel from a satellite in outer space to a dish aerial on the ceiling of the home. In a cable television, light travels through optical fibres to the home. In a terrestrial television, electromagnetic waves travel from a transmitter on Earth to a television aerial in the home. (a) State the region of the electromagnetic spectrum used in each of these systems. satellite terrestrial [2] (b) A satellite is in orbit at a height of 36 000 km above the Earth’s surface. Calculate the time it takes for a signal to travel from the satellite to the dish aerial on Earth. time = [2]