2025 ZHSS Physics Prelim Paper 2 QP

1 [Turn over ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2025 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number PHYSICS 6091 /02 Paper 2 28 August 2025 1 hour 45 minutes Additional Materials: NIL READ THESE INSTRUCTIONS FIRST Write your name, class and register number in the spaces at the top of this page and on all separate answer paper used. Write in dark blue or black pen. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided on the question paper. Section B Answer one question. For Examiner’s Use Write your answers in the spaces provided on the question paper. Section A 70 Section B 10 Total 80 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. Setter: Mr Tan Jun Hong and Mrs Ngiam-Fok Kar Yin Vetter: Sec 4E Pure Physics Teachers This document consists of 21 printed pages and 1 blank page.

2 Section A Answer all the questions in this section in the spaces provided. 1 A drone was initially flying towards the west at a velocity of 15 m/s at time, t = 0 s. It then decelerated uniformly until it came to a stop at t = 10 s. The drone then turned and its velocity increases at a uniform rate of 2.0 m/s 2 for another 12 seconds towards the east. (a) Sketch, in the axes provided below in Fig. 1.1, the velocity-time graph of the drone. Fig. 1.1 [2] (b) Calculate the deceleration of the drone at t = 0 s. deceleration = [1] velocity / ms-1 Time / s 20 10 0 -10 -20 -30 5 10 15 20 25

3 [Turn over (c) Calculate the average speed of the drone for the entire duration of flight. average speed = [2] 2 Fig. 2.1 shows a toy water rocket. Fig. 2.1 The rocket is half-filled with water and connected by rubber tubing to a pump. (a) Air is then pumped into the rocket so that the pressure of the air inside the rocket increases. Explain, in terms of particles, why the air in the rocket exerts a pressure on the walls of the rocket. [2]

4 (b) When the air pressure in the rocket is high, the rubber tubing is removed from the rocket. The water in the rocket is expelled downwards. Use Newton’s laws of motion to explain why the rocket begins to accelerate upwards. [2] (c) As the water is expelled from the rocket, the upward acceleration of the rocket decreases. Suggest two reasons for the change in the acceleration of the rocket. [2] 3 A worker carries a ladder horizontally on his shoulder as shown in Fig. 3.1. His shoulder acts as a pivot. Fig. 3.1 The weight of the ladder is 80 N. (a) Explain what is meant by moment of a force. [1]

5 [Turn over (b) The centre of mass of the ladder is a horizontal distance of 0.90 m from the worker’s shoulder. Calculate the moment about the worker’s shoulder of the weight of the ladder. moment = [1] (c) A bucket of weight 87 N is suspended from the ladder at a horizontal distance of 1.3 m from the worker’s shoulder. The worker keeps the ladder horizontal by exerting a vertical force at point L. L is a horizontal distance of 0.54 m from his shoulder. Determine the size and direction of the force exerted at L. size of force = direction = [3]

6 4 Faith’s toy consists of a flexible track and a model car as shown in Fig. 4.1. Fig. 4.1 Faith first holds the car stationary at point A which is 0.45 m above the horizontal sections of track BC and FG. She then releases the car which travels towards point B. Both air resistance and friction between the car and the track are negligible. (a) State the principle of the conservation of energy. [1] (b) Calculate the speed of the car when it reaches B. speed = [2]

7 [Turn over (c) Faith was very confident that when the car is released at A, it will follow the track along the route ABCDEFG. Explain if she is correct. [2] 5 Fig. 5.1 shows a man standing underneath an outdoor heater on a cold evening. Fig. 5.1 Gas in the cylinder at the base of the heater is the fuel for the heater. When the heater is operating, the gas travels to the top of the heater where it burns. A metal screen surrounding the burning gas is heated by the burning gas until it is red- hot. The hot metal screen warms the man who is standing underneath it. metal hood red-hot metal screen pullover gas cylinder shiny surface

8 (a) Describe two possible ways how thermal energy within the red-hot metal screen is transferred to the man. [2] (b) At the top of the heater is a metal hood that has a shiny lower surface. Explain why this makes the energy transfer from the metal screen more efficient. [1] (c) During the evening, the temperature of the environment starts to decrease to as low as 5.0 OC. The man puts on his black pullover. Explain how the pullover keeps him warm. [2] 6 A ray of blue enters a glass prism of sides XYZ as shown in Fig. 6.1. The ray is also shown incident on a different side of the prism after passing through the prism. Fig. 6.1 The ray of blue light strikes the side XY of the prism at an angle equal to its critical angle c. X Y Z

9 [Turn over (a) State what is meant by the critical angle. [1] (b) On Fig. 6.1, mark and label the angle of incidence i and the angle of refraction r for the blue light as it enters the prism. [1] (c) On Fig. 6.1, continue the path of the blue light after it strikes the side XY of the prism. [1] (d) The glass prism is replaced by another prism which has a lower refractive index. Refraction of the blue ray now occurs at side XY. State two reasons why this occurs. 7 Most of the energy emitted by the Sun is in three regions of the electromagnetic spectrum. (a) The name of one of these three regions is the ultraviolet region. (i) State the names of all three regions in order of increasing frequency. [2] (ii) Some of the ultraviolet radiation emitted by the Sun reaches the surface of the Earth. Give one possible damaging effect of ultraviolet radiation on the human body and the property of ultraviolet radiation that causes this damage. [2] 1. 2. [2] Lowest frequency: Highest frequency: Intermediate frequency: Damaging effect: Property:

10 (b) The wavelength of one of the waves emitted by the sun is 500 nm. Calculate the frequency of this wave in space. frequency = [2] 8 The power supply in an electric circuit is a battery of electromotive force (e.m.f.) 12 V. Fig. 8.1 shows the circuit that includes two resistors, one thermistor, one voltmeter, one wire YZ and one open switch, S1. Fig. 8.1 YZ is a straight, horizontal section of connecting resistance wire of 2