2025 AMKSS Pure Physics Prelim P2 + MS

2 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 Answer all the questions. 1. Fig 1.1 shows a uniform beam which is supported by two light cables, AB and AC. They are attached to a vertical steel cable from a crane. The beam is at rest. Fig 1.1 (a) Explain why the centre of gravity of the beam shown in Fig 1.1 must be vertically below A when the beam is at rest. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………[2] (b) A student made this statement: “The tension in the vertical steel cable and the weight of the beam are an action and reaction pair of forces.” Explain with two reasons if you agree or disagree with the statement. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………[2] (c) State the two conditions for a system in equilibrium. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………..……..[2] 2025 Phy Set 5

3 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 [Turn Over 2. A student with a weight of 500 N moves down a long slide as shown in Fig 2.1 on earth. Fig 2.1 The student moves from rest from X which is located at the top end of the slide. The surface of the slide is rough. He experiences an average resistive force of 70 N as he slides from X to Y. The kinetic energy of the student at Y is 300 J. The decrease in the gravitational potential energy of the student as he moves from X to Y is 3000 J. (a) State the law of conservation of energy. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………[2] (b) Obtain the mass of the student. mass=……………..[1] (c) Determine the speed of the student at Y. speed=……………………..[2] (d) Calculate the length of the slide. You may assume that the air resistance experienced by the student while sliding from X to Y is negligible. length of the slide=………………………….[2]

4 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 (e) At end Y of the slide, the student is brought to rest by a board as shown in Fig 2.2. Fig 2.2 A spring connects the board to a fixed point. The student hits the board so that it moves to the right and compresses the spring. The speed of the student becomes zero when the elastic potential energy of the spring has increased to its maximum value of 140 J. Calculate the percentage efficiency of the transfer of the kinetic energy of the child at Y to the elastic potential energy of the spring. percentage efficiency=……………………………..[1] 3. A uniform plank of length 4.00 m and weight 800 N is suspended by two strings at X and Y from the ceiling as shown in Fig 3.1. A box of 2.5 kg is placed on the plank. Fig 3.1 (a) Label clearly the following forces on Fig 3.1. (i) Weight of plank (Wplank) (ii) Weight of the box (Wbox) (iii) Tension in X(Tx) (iv) Tension in Y(Ty) [2] box

5 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 [Turn Over (b) Given that the plank is in equilibrium, calculate the tensions in X and in Y. Tx=…………………………… Ty=…………………………...[3] 4. Fig 4.1 shows the interior of a spray can. Fig 4.1 It is first filled with liquid paint and then injected with gas. The spray cap traps the highly compressed gas within the can. When used, some of the liquid paint leaves the can and the pressure inside the can decreases. (a) Explain, using the motion of molecules, how the compressed gas exerted a pressure on the walls of the spray can. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………...…….[2]

6 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 (b) After using much of the liquid, the rate at which the liquid paint is sprayed out decreases. Using ideas about molecules, explain why this happens. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………....[2] 5. Fig 5.1 shows part of a hydraulic braking system of a car. Fig 5.1 The force F1 exerted by the driver’s foot on the brake pedal moves piston X. The volume between piston X and piston Y is filled with oil which is incompressible. The force F2 exerted by the oil moves piston Y. This force is applied to the brake mechanism in the wheels of the car. The cross-sectional area of piston X is 5.00 cm2 and F1 = 100 N (a) Calculate the pressure, in Pa, exerted on the oil by piston X. pressure=……………………….[2] (b) With reference to Fig 5.1, explain why force F2 is greater than force F1. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..[2] (c) Explain why piston Y moves a shorter distance than piston X. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..[2] Piston X Piston Y

7 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 [Turn Over (d) Suggest why the braking system will not work properly if the oil contains bubbles of air. ………………………………………………………………………………………………………………………………………………………………………………….……………………….[1] 6. Fig 6.1 shows a transverse wave travelling along a rope. The positions of the wave at the time intervals t = 0.0 s and t = 2.0 s as labelled. Fig 6.1 (a) Calculate the speed of the wave. speed=………………..[1] (b) Determine the period of the wave. period=………………….[2] (c) X is a particle on the wave at t= 0.0 s. On Fig 6.1, mark the new displacement of X at t= 6.0 s. Label the new vertical position as Y. [1]

8 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 7. Fig 7.1 shows an experiment set up (not drawn to scale) to investigate how light travels from water to air. A metre ruler with a small laser beam bulbs are fixed at 10.0 cm intervals is placed vertically into water. The refractive index of water is 1.33. Fig 7.1 (a) Fig 7.1 shows a ray of light from bulb 1. The point of incidence on the water surface is d cm from the metre ruler and the water surface is at the 65.0 cm mark of the metre ruler. Given that the angle of incidence, i is 45°, calculate d. d=…………………[1] (b) Calculate the angle of refraction, r, in the air. r=……………………[2] (c) Calculate the critical angle of water. critical angle=……………………..[2]

9 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 [Turn Over (d) With the metre ruler in the same position, each light bulb is switched on one at a time and each laser light aimed at the same point of incidence, with the same d value as calculated in (a). Explain if total internal reflection will occur when bulb 2 is fixed at the 20 cm mark of the metre ruler. You may support your answer with relevant calculations. calculations: …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………....[2] 8. A student measures the speed of sound using an echo from a cliff. She stands facing the cliff and claps her hands as shown in Fig 8.1. Fig 8.1 (a) The echo arrives 4.0 s after she claps her hands. She walks 220 m towards the cliff and then claps her hands again. The echo now arrives 2.6 s after she claps. Calculate the speed of sound using these data. Give your answer to an appropriate number of significant figures. speed=…………………….[2] student cliff

10 AMKSS 4E PRELIM Exam 6091(Revised)/02/2025 (b) The student produces a musical sound. State how the sound changes when (i) The amplitude of the sound increases. ……………………………………………………………………………………..…….[1] (ii) The wavelength of the sound increases. ……………………………………………………………………………………..…….[1] 9. A student heats a metal block, M until it reaches a temperature of 100 °C. He transfers the metal block into a beaker containing 200 g of water at 25 °C as shown in Fig 9.1. Fig 9.1 The temperatu