ACS Exp Prelim 2024 P2 final

This document consists of 21 printed pages. PRELIMINARY EXAMINATION 2024 YEAR 4 EXPRESS PHYSICS 6091 / 02 Friday 2 August 2024 1 hour 45 minutes READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Section B Answer only one of the two alternative questions in this section. 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. 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. Unless otherwise stated, take gravitational field strength, g, to be 10 N kg-1. For Candidate’s use (Section B): Circle the question you would like the examiner to mark for Section B. You may circle only one of the options. Q11 Either Q11 Or Index Number Name For Examiner’s use Section A Section B Sig. Fig. penalty Unit penalty TOTAL

Y4Exp Physics Prelim 2024P2 Page 2 of 21 Section A Answer all the questions in this section. 1 A car approaches a set of traffic lights. The lights change to red at time t = 0 s. Fig. 1.1 shows how the speed of the car changes with time. The car starts to slow down a short time after the lights change to red. (a) Using Fig 1.1, (i) state the time between the lights changing to red and the car starting to slow down. [1] (ii) determine the average speed of the car from time t = 0 s to t = 4.0 s. Average speed = ___________________ [2] (b) Describe the motion of the car between time t = 4.0 s to t = 7.0 s. [2] Fig. 1.1

Y4Exp Physics Prelim 2024P2 Page 3 of 21 2 Fig. 2.1 shows a type of balance that is used for measuring mass. A rigid rod , of negligible mass, is pivoted about a point 6.2 cm from the centre of a pan which is attached to one end. The object being measured is placed on the centre of this pan. A spring, attached to the rod 1.8 cm from the pivot, is attached at its other end to a fix point P. The force of the spring is directly proportional to its extension over the full range of operation of the balance. A pointer, on the other side of the pivot, is set against a millimetre scale which is a distance 52.6 cm from the pivot. When the system is in equilibrium with no mass on the pan, the rod is horizontal and the pointer indicates a reading on the scale of 86 mm. An object of mass 0.472 kg is now placed on the pan. As a result, the pointer moves to indicate a reading of 123 mm on the scale when the system is again in equilibrium. The increase in the length of the spring is approximately 1.3 mm. (a) State what is meant by moment of a force. [1] (b) Calculate the magnitude and direction of the moment of the weight of the object about the pivot. Magnitude of Moment = ___________________ Direction of Moment = ___________________ [3] Fig. 2.1

Y4Exp Physics Prelim 2024P2 Page 4 of 21 (c) Use your answer in (b) to determine the increase in the tension in the spring due to the 0.472 kg mass. ∆Tension = ___________________ [2] 3 A cyclist travels at an initial speed of 5.0 m/s. A ball rolls in front of the bicycle at time t = 0 s. The cyclist applies a force on the brake lever. This increases the pressure in the oil by 1.2 × 106 Pa. Fig. 3.1 shows the hydraulic braking system of the cycle. The cross-sectional area of piston R and piston S are 5.0 × 10–5 m2 and 1.5 × 10–3 m2 respectively. (a) Refer to Fig 3.1, (i) calculate the force F applied by the brake lever to piston R. Force F = ___________________ [2] Fig. 3.1 (not drawn to scale)

Y4Exp Physics Prelim 2024P2 Page 5 of 21 (ii) explain why the force applied to each of the brake pads is larger than F. [2] (b) Determine the distance moved by piston R if each brake pad of piston S moves 0.20 mm. Distance = ___________________ [2] 4 Fig. 4.1 shows how the air pressure varies with time for the sound waves from two sources A and B. When the amplitude of a wave is higher, the higher chance the air particles will be compressed together in an air column, hence result ing in a higher pressure. In other words, the amplitude of a wave is directly proportional to pressure of air. Fig. 4.1

Y4Exp Physics Prelim 2024P2 Page 6 of 21 (a) Use Fig. 4.1 to describe and explain what differences would be heard in the sound from the two sources A and B. [4] (b) In a sound wave, (i) what are the regions which are at pressures slightly below the atmospheric pressure known as? [1] (ii) what wave property describes the shortest distance from one compression to the next compression? [1]

Y4Exp Physics Prelim 2024P2 Page 7 of 21 5 Visible light rays undergo refraction when passing through a converging lens made of optical glass. This property means that the image formed by the lens may have different characteristics from the object. (a) Fig. 5.1 shows the lens diagram of one such converging lens. Fig. 5.1 (i) When an object of height 1.5 cm is at a distance 2.0 cm away from the optical centre C of the lens, a virtual image is formed at a distance 4.0 cm away from the optical centre C of the lens. Determine, using a scaled diagram, the focal length f of the converging lens, and the height hi of the image formed. Draw your scaled diagram directly on the grid in Fig. 5.1. The scale is given on the bottom left of the grid. f = ___________________ h i = ___________________ [4] (ii) Describe what will happen to the image as the object is slowly moved closer towards the lens. [1] C 1.0 cm 1.0 cm

Y4Exp Physics Prelim 2024P2 Page 8 of 21 (b) The lens in Fig. 5.1 is made of optical glass, and is transparent to visible light, but may not be transparent to other components of the electromagnetic wave spectrum. To investigate this further, a selected range of wavelengths of electromagnetic waves were tested. The electromagnetic waves were directed toward the lens, and the transmittance (proportion of light that passes through the lens) was measured. The results were tabulated. Range of tested wavelength/nm Transmittance / % Component of electromagnetic wave spectrum 100 - 400 0 X 400 - 700 95 Visible light 700 - 1200 95 Y Name the components of the electromagnetic wave spectrum that X and Y correspond to. X: ______________________ Y: ______________________ [2] 6 Fig. 6.1 shows an electrical circuit consisting of a lamp L, semiconductor diode D and a resistor R. The resistor R has a known value of 12.0 Ω The current I 2 passing through resistor R is 0.50 A. The electromotive force (e.m.f.) in the circuit is 12.0 V. Fig. 6.1

Y4Exp Physics Prelim 2024P2 Page 9 of 21 Fig. 6.2 shows a plot of the