Dunman 2025 Physics 6091 Prelim P2

This document consists of 26 printed pages. DUNMAN SECONDARY SCHOOL CANDIDATE NAME CLASS INDEX NUMBER PRELIMINARY EXAMINATION 2025 SECONDARY 4 EXPRESS PHYSICS 6091/02 Paper 2 Structured and Free Response 25 August 2025 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number 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. 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.

2 6091/02/PRELIM/4EXP/2025 Section A Answer all questions. 1 A ball rolls down a slope, as shown in Fig. 1.1. The metre rule shows the position of the ball at times t = 0.0 s, t = 1.0 s, t = 2.0 s and t = 3.0 s. Fig. 1.1 (a) Explain how Fig. 1.1 shows that the ball is accelerating. ……………………………………………………………………………………………….……….. …………….………………………………………………………………………….…….…..... [1] (b) Calculate the average speed of the ball between t = 1.0 s and 3.0 s. average speed = …………..……..……….. [2] (c) Two of the forces that act on the ball are air resistance and weight. State the changes to these forces, if any, as the ball accelerates. air resistance: ..…………………………………………………………………………….……….. weight: ……......…………………………………………………………………………….……….. [2] t = 0.0 s t = 1.0 s t = 2.0 s t = 3.0 s metre rule slope

3 6091/02/PRELIM/4EXP/2025 (d) On Fig. 1.1, draw the direction of friction between the ball and ground at t = 2.0 s. [1] [Total: 6]

4 6091/02/PRELIM/4EXP/2025 2 A crankshaft is a shaped metal bar that is part of a car engine. It is free to rotate about an axis, as shown in Fig. 2.1. Fig. 2.1 When the crankshaft is horizontal, a vertical force F of 7800 N acts downwards on the crankshaft at P. This causes the crankshaft to rotate. The distance between P and the axis of the crankshaft is 0.050 m. (a) State what is meant by the moment of a force. …………………………………………………………………………………………….………….. …………….………………………………………………………………………….…….….... [1] (b) Calculate the moment of F about the axis of the crankshaft when the crankshaft is horizontal. moment = …………..……..……….. [2] crankshaft axis of crankshaft direction of rotation 0.050 m F P

5 6091/02/PRELIM/4EXP/2025 (c) The size and direction of the vertical force F, acting on the crankshaft at P, remain constant. Explain why the moment of F decreases as the crankshaft rotates through a small angle. ………………………………………………………………………………………….…………….. ………………………………………………………………………………………….…………….. …………….…………………………………………………………………………..……….... [1] [Total: 4]

6 6091/02/PRELIM/4EXP/2025 3 Fig. 3.1 shows a syringe mounted vertically in a block of wood and sealed at one end. A plunger is free to move inside the syringe. There is trapped air in the syringe. Fig. 3.1 The air inside the syringe exerts a pressure on the walls of the syringe. (a) Define pressure. ……………………………………………………………………………………………….……….. ……………………………………………………………………………………………….……….. …………….………………………………………………………………………….………...... [1] (b) Explain how the air molecules in the cylinder of the syringe create a pressure. ……………………………………………………………………………………………….……….. ……………………………………………………………………………………………….……….. ……………………………………………………………………………………………….……….. ……………………………………………………………………………………………….……….. ……………………………………………………………………………………………….……….. …………….………………………………………………………………………….…….…..... [3] plunger syringe trapped air wood sealed end

7 6091/02/PRELIM/4EXP/2025 (c) A 20 N weight is placed on top of the plunger. The plunger moves down slowly so that the temperature of the air inside the syringe does not change. Before the weight is placed on top: • the pressure of the air inside the syringe is 1.0 × 105 Pa. • the volume of the air is 60 cm3. The cross-sectional area of the plunger is 1.5 × 10−4 m2. Calculate the pressure of the air in the syringe after the plunger stops moving. pressure = ……………..……….. [2] [Total: 6]

8 6091/02/PRELIM/4EXP/2025 4 Fig. 4.1 shows an elevator (lift) that is supported by a cable. Fig. 4.1 (not drawn to scale) The cable passes around the axle of an electric motor and over a pulley. The cable is then attached to a concrete block that has the same mass as the empty elevator. As the elevator moves up, the concrete block moves down. (a) Explain why very little work is done by the electric motor when lifting up the empty elevator. …………………………………………………………………………………………….………….. …………………………………………………………………………………………….………….. …………………………………………………………………………………………….………….. …………….………………………………………………………………………….…….…..... [2] (b) Several people of total weight 58 00 N are travelling upwards at constant speed in the elevator. They rise through a distance of 25 m in 28 s. Calculate the minimum power output of the electric motor. power = ……………..……….. [2] [Total: 4] pulley concrete block cable electric motor elevator axle

9 6091/02/PRELIM/4EXP/2025 5 Fig. 5.1 shows a soldering iron. Solder is a mixture of metals used to make a permanent contact between electrical wires. Fig. 5.1 The heating element raises the temperature of the metal tip. When solder is placed against the tip, the solder melts over the wires to be joined. When the solder cools, it solidifies and the permanent connection is made. The working temperature of the metal tip is 360 °C. (a) The heating element is rated at 24 V, 3.5 A. The heating element is switched on. The temperature of the metal tip rises from 20 °C to 320 °C in the first 10 s. (i) Calculate the electrical energy supplied to the heating element in the first 10 s. electrical energy = ……………..……….. [2] (ii) The metal tip is made of copper and has a mass of 2.8 g. The specific heat capacity of copper is 0.39 J / (g °C). Calculate the thermal energy (heat) gained by the metal tip in the first 10 s. thermal energy = ……………..……….. [2] metal tip heating element

10 6091/02/PRELIM/4EXP/2025 (iii) Explain the difference in the answers for (i) and (ii). ………………………………………………………………………………....….…….......... ………………………………………………………………………………....………..... [1] (b) Describe, in terms of free electrons, the process by which heat is transferred through the metal tip. ……………………………………………………………………………….……………………….. ……………………………………………………………………………….……………………….. ……………………………………………………………………………….……………………….. …………….……………………………………………………………….………….……….... [2] [Total: 7]