YCKSS Prelim P2

Name: Index Number: Class: YIO CHU KANG SECONDARY SCHOOL O-LEVEL PRELIMINARY EXAMINATION 2024 SECONDARY FOUR EXPRESS PHYSICS 6091/02 Paper 2 1 hour 45 minutes 10 September 2024 (Tuesday) No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on the cover page. Write in dark blue or black ink. You may use a soft 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 Section A / 70 Section B / 10 Total / 80 Parent’s / Guardian’s signature Setter: Mr Brandon Chin This document consists of 23 printed pages and 1 blank page.

2 4E O-LEVEL PRELIM EXAM 2024 6091/02 SECTION A Answer all questions in this section in the spaces provided. 1 Fig. 1.1 shows a bungee jumper falling from a bridge above a river. Fig. 1.1 The man starts from position A. The elastic cord starts to stretch at position C and he stops for the first time at position D. He continues to rise and fall. Fig. 1.2 shows how the velocity of the man varies with time t. Fig. 1.2 (a) State the difference between the positive velocity and negative velocity of the bungee jumper. ……………………………………………………………………………………………….…. ………………………………………………………………………………………………. [1] t/s 1 2 3 4 6 5 Position A Position B Position C Position D at the top cord starts to stretch at the lowest point

3 4E O-LEVEL PRELIM EXAM 2024 6091/02 1 (b) In the first 1.4 s, the acceleration is uniform. Using values from Fig. 1.2, determine the acceleration of the man in the first 1.4 s. acceleration = ………………………………… [2] (c) With reference to Fig. 1.2, state the time when the man is at position D. ………………………………………………………………………………………...…….. [1] (d) (i) State the two forces acting on the man at position D. ………………………………………………………………………………………... [1] (ii) Explain, in terms of the forces acting, why the man is accelerating upwards at position D. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… ……………………………………………………………………………………….. [2]

4 4E O-LEVEL PRELIM EXAM 2024 6091/02 2 An aircraft flies at a constant height. The force from the engine of the aircraft and air drag together produce a force of 36 kN on the aircraft due east as shown in Fig. 2.1. The wind produces a force of 12 kN towards the south. Fig. 2.1 Draw a scale drawing to show the resultant force acting on the aircraft. Use your drawing to determine the size of the resultant force and the angle between the resultant force and east. scale = .................... cm : .................... N size of resultant force = ............................................................... angle = ............................................................... [3] 36 kN 12 kN north

5 4E O-LEVEL PRELIM EXAM 2024 6091/02 3 A student designed a box which can slow down the process of melting for ice-cream cakes as they are delivered from the restaurant to the parties. The box is made of expanded polystyrene with a cold pack attached to its cover as shown in Fig. 3.1. (a) State and explain two features of the box which help to slow down the melting of the ice-cream cake. feature 1: ……………………………………………………………………………………….. explanation: ……………………………………………………………………………………. …………………………………………………………………………………………………… feature 2: ……………………………………………………………………………………….. explanation: ……………………………………………………………………………………. …………………………………………………………………………………………………… [4] (b) Suggest one improvement that the student could make to the design of the box to further slow down the melting of the ice-cream cake. …………………………………………………………………………………………………… ……………………………………………………………………………………………….. [1] cold pack cover expanded polystyrene Fig. 3.1

6 4E O-LEVEL PRELIM EXAM 2024 6091/02 4 Ultrasound and X-rays are both used in medical imaging. (a) An ultrasound scanner can emit and detect reflected sound waves. To produce an image of an unborn child, an ultrasound scanner is placed on the mother’s skin as shown in Fig. 4.1. Fig. 4.2 shows pulses detected by the ultrasound scanner. Pulse A is the emitted pulse and pulse B is the first pulse that returns from the unborn child. (i) Define what is meant by ultrasound. ............................................................................................................................. ........................................................................................................................ [1] (ii) The average speed of ultrasound in human tissue is 1500 m/s. Using the information in Fig. 4.2, calculate the distance between the ultrasound scanner and the unborn child. distance = ......................................................... [2] Fig. 4.1 Fig. 4.2 image of an unborn child ultrasound scanner

7 4E O-LEVEL PRELIM EXAM 2024 6091/02 4 (b) An X-ray detector is placed just below an arm. Fig. 4.3 shows an X-ray image of the arm with a broken bone and human tissue which are formed on a screen by the detector. Fig. 4.3 The wavelength of the X-rays used is 2.0 × 10−9 m. (i) Calculate the frequency of the X-rays. frequency = ......................................................... [2] (ii) Suggest one reason why X-rays are not used to form an image of an unborn child. ............................................................................................................................. ........................................................................................................................ [1]

8 4E O-LEVEL PRELIM EXAM 2024 6091/02 5 Electrical energy distribution takes place in a country through a network of transmission cables, as shown in Fig. 5.1. A power station generates 100 MW of power at a voltage of 25 kV. Fig. 5.1 Transformer A, which links the power station to the transmission cables, has 4000 turns in the primary coil and 44000 turns in the secondary coil. (a) Calculate the current in the secondary coil of transformer A, assuming the transformer is 100% efficient. current = ………………………………… [3] (b) Explain why electrical transmission in the cables is typically at a very high voltage. …………………………………………………………………………………………………… …………………………………………………………………………………………………… ……………………………………………………………………………