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