2023 XMS P2 PRELIM QP

2 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use Section A Answer all questions in this section. 1 A solid block is placed in water and in diesel in turn. In each liquid, the block remains stationary when it is partially submerged. The block is 75% and 86% submerged in water and in diesel respectively. The density of water is 1000 kg m-3. (a) Draw a free-body diagram of the block when it remains stationary while partially submerged in a liquid. Label the forces acting on the block clearly. [1] It has been verified that when an object is partially or totally submerged in a liquid, the upthrust experienced by the object is equal to the weight of the liquid that is displaced by the object: Upthrust = Weight of liquid displaced (b) Since the solid block mentioned above remains stationary when it is partially submerged in (either of the two) liquids, (i) comment on the relationship between the weight of the block and the weight of (either of the two) liquids displaced by the block, ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. [1] (ii) comment on the relationship between the weight of the water displaced by the block and the weight of the diesel displaced by the block. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. [1]

3 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use (c) Hence, find the density of diesel. density of diesel = ……………………… [3] [Total: 6] 2 Figure 2 shows a cargo ship experiencing a big horizontal force T due to an oncoming tsunami (not drawn to scale). The force on the ship by the tsunami T, is 45 kN and acts 10 m above sea level. The weight of the ship W, is 400 kN and acts from point C. The upthrust on the ship by sea water is U, 400 kN and acts from point D. Figure 2 (a) At the time shown in Figure 2, the ship is over-turning about pivot point E. (i) Suggest the direction of the over-turning moment at this time. direction of over-turning moment is ……………………………. [1] (ii) Calculate the magnitude of the resultant over-turning moment. over-turning moment = ……………………. [2]

4 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use (b) Without changing the physical attributes of the cargo ship, describe one way to make the ship more stable and reduce the probability of it over-turning. …………………………………………………………………………………………... …………………………………………………………………………………………... [1] [Total: 4] 3 Figure 3 shows a section of a swimming pool with its drainage hole being plugged. The steel plug is 1.9 kg and it covers the circular drainage hole of 0.02 m2. The density of water in the pool is 1000 kg m-3. Figure 3 (a) Calculate the force exerted by the water on the steel plug. force by water on plug = ……………………. [3] (b) Hence, calculate the force exerted by the two side slabs on the steel plug. State the direction of this force. force by slabs on plug = …….……………… direction of force = ……………………. [3] [Total: 6] Steel plug

5 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use 4 Figure 4 shows a water heater. Figure 4 (a) Describe the process by which thermal energy is transferred throughout the water. …………………………………………………………………………….…………..... …………………………………………………………………………….………..…... …………………………………………………………………………….…..………... …………………………………………………………………………….…………..... [2] (b) Suggest a material to use as lagging and explain your choice. ………………………………..…………………………………………….…………... ………………………………………..…………………………………….…………... ………………………………………..…………………………………….…………... [2] (c) Suggest what the exterior colour and texture of the water heater should be and explain your choices. ………………………………..…………………………………………….…………... ………………………………………..…………………………………….…………... ………………………………………..…………………………………….…………... [2] [Total: 6]

6 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use 5 A thermocouple is used to measure the temperature of a thermistor. Its cold junction is placed in a beaker of anti-freeze liquid at 0°C while its hot junction is placed in contact with the thermistor. When the temp erature of the thermistor is 30 °C, the e.m.f. measured by the thermocouple is 0.5 mV. (a) Calculate the e.m.f. measured by the thermocouple when the temperature of the thermistor is 66°C. e.m.f. measured = ……………………. [2] (b) Describe how the temperature of the thermistor T changes with the potential difference across it V, when the thermistor is connected in series with a fixed resistor in an electric circuit. ……………………………………………………………………………………...…… ……………………………………………………………..……………………………. [1] [Total: 3] 6 Figure 6a shows water waves in a pool of different depths. The frequency of the water waves in the pool is 50 Hz. Figure 6a (a) State what is meant by frequency of 50 Hz. ……………………………………………...…………………………………………… ……………………………………………………………………………...…………… [1] U V Z 30 m 15 m Y

7 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use (b) Calculate the speed of the water waves in region UV. speed = ……………………. [2] (c) Describe how the depth of water affects the speed of the water waves in the pool. ………………………………………………………………………………...………… ……………………………………………………………………………………...…… [1] (d) Part of Figure 6a has not been drawn correctly. Complete Figure 6b to show how the diagram can be drawn more correctly. [1] Figure 6b [Total: 5] 7 Figure 7 shows a ray of light being projected from air into a glass prism. Figure 7 U V Z 30 m 15 m Y P Q Y X Z 40 ° 70 °

8 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use The ray hits external surface XY at point P. It then hits the internal surface YZ at point Q and exits along the surface of YZ. (a) Calculate the refractive index of the glass. refractive index = ……………………. [2] (b) Calculate the angle of incidence of the ray at point P. angle of incidence = ……………………. [2] [Total: 4] 8 Figure 8a shows a cling wrap (made of insulator plastic) being peeled off itself from a roll. The peeling action creates static charges on the two sides that were originally sticking together. Figure 8b shows the peeled cling wrap being used to wrap around a cabbage to maintain its freshness. Figure 8a Figure 8b (a) (i) Suggest the types of charge on underside M and topside N of the cling wrap. Describe how the sides become charged as you suggested. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. [2]

9 6091/Physics/Paper 2/2023 Prelim Exam For Examiner’s Use (ii) Hence explain why the cling wrap can stick onto itself to form a seal to maintain the freshness of the cabbage. ……………………………………………………………………………………. ……………………………………………………………………………………. [1] (b) Figure 8c shows a neutral ceramic bowl. Figure 8c On Figure 8c, sketch a cling wrap stretching just over the rim of the bowl. Explain why the cling wrap can stick onto the ceramic bowl to form a seal. …………………………………………………………………………………………... ………………………………………………………