NJC 2022 Prelim P2

[Turn over NATIONAL JUNIOR COLLEGE SENIOR HIGH 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER PHYSICS Paper 2 Structured Questions Candidate answers on the Question Paper. 9749/02 23 August 2022 2 hours No Additional Materials are required. READ THE INSTRUCTION FIRST Write your subject class, registration number and name in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use a HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Answers all questions. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 10 2 / 10 3 / 10 4 / 8 5 / 8 6 / 14 7 / 20 Total (80) This document contains 22 printed pages and 2 blank pages.

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4 Answer all the questions in the spaces provided. 1 As a ship is approaching the dock at 45.0 cm s–1, an important piece of landing equipment needs to be thrown to it before it can dock. This equipment is thrown at 15.0 m s –1 at 60.0° above the horizontal from the top of a tower at the edge of the water, 8.75 m above the ship's deck as shown in Fig. 1.1. For this equipment to land at the front of the ship's deck, the distance from the dock to the ship when the equipment is thrown should be D as shown in Fig.1.1 Fig 1.1 (a) Assuming that air resistance is negligible. (i) Show that the time of flight of the equipment is 3.21 s. [1] (ii) Hence, determine the value of D. D = ………………………………………………… m [3] (b) If air resistance is not negligible, comment on whether D should be longer or shorter. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………. [2]

[Turn over 5 (c) Sketch and label clearly on the same axes in Fig 1.2, a graph to show the variation with time of flight t of the vertical component of velocity Vy of the equipment during its flight if (i) air resistance is negligible, (ii) air resistance is not negligible. For both graphs, take upwards direction as positive. Fig 1.2 [4] [Total: 10] Vy / m s–1 t / s 0

6 2 Two blocks travel directly towards each other along a horizontal, frictionless surface. The blocks collide, as illustrated in Fig. 2.1. Fig. 2.1 Block A has mass 3M and block B has mass M. Before the collision, block A moves to the right with speed 0.40 m s–1 and block B moves to the left with speed 0.25 m s–1. After the collision, block A moves to the right with speed 0.20 m s–1 and block B moves to the right with speed v. (a) (i) Use Newton’s laws of motion to explain why the change in mo mentum of each block is equal in magnitude and opposite in direction. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .…………………………………………………………………………………………………… [4] (ii) Hence, explain whether it is possible for both blocks to be at rest simultaneously during the collision. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .…………………………………………………………………………………………………… [2]

[Turn over 7 (b) (i) Determine speed v. v = …………………………………………….. m s–1 [2] (ii) Deduce whether the collision is elastic or inelastic. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .………………………………………………………………………………………………………. .…………………………………………………………………………………………………… [2] [Total: 10]

8 3 Fig. 3.1 shows the front view of a container ship. Fig. 3.1 The line of symmetry of the ship is known as the centre-line. An important part of the ship is the ballast keel, a vertical downward extension of the ship’s hull, that is loaded to keep the centre of gravity G of the boat low as shown in Fig. 3.1. When the ship floats in the sea, the upthrust of the ship is equal in magnitude but opposite in direction to the weight of the ship. (a) Explain (i) what is meant by the centre of gravity of the ship, ……………………………………………………………………………………………………...... ……………………………………………………………………………………………………...... ……………………………………………………………………………………………………. [2] (ii) the origin of the upthrust acting on the ship. ……………………………………………………………………………………………………...... ……………………………………………………………………………………………………. [1] (b) The ship has a mass of 2.20 × 108 kg and the density of seawater is 1030 kg m–3. Calculate the volume of seawater displaced by the ship. volume = ……………………………………………….. m3 [2] keel centre-line containers G

[Turn over 9 (c) A ship will roll on its sides due to the wind and the water waves. Fig 3.2 shows ship on its side at a particular instant. Fig. 3.2 The upthrust acts through the centre of gravity of the displaced fluid, known as the centre of buoyancy B shown in Fig. 3.2. (i) On Fig. 3.2, mark with arrows labelled W for the weight and labelled U for the upthrust. [1] (ii) By reference to the completed diagram of Fig. 3.2, explain why the ship will not overturn. ……………………………………………………………………………………………………...... ……………………………………………………………………………………………………...... ……………………………………………………………………………………………………. [2] (d) When the ship is fully loaded with containers (you may assume the containers are secured and will not shift), the centre of gravity G will be at a higher position along the centre-line. Draw relevant forces on Fig. 3.3 to explain the danger of a fully loaded ship rolling to its side. Fig. 3.3 ……………………………………………………………………………………………………............... …………………………………………………………………………………………………….......... [2] [Total: 10] G B

10 4 (a) A resistor “ladder” with 2 stages “R-2R” resistors, with values of R and 2R, are connected to an ideal cell of e.m.f. V as shown in Fig. 4.1. Fig. 4.1 (i) Show that the effective resistance between junction A and M is R. [1] (ii) Determine the potential at junction A in terms of V. potential at A in terms of V ……………..…………………………………….. [2] M N A B R R R R 2R 2R V