CHS 2021 - Sec 4 PHYSICS Prelim Exam PAPER 2 - Questions

1 Name: Index Number: Class: CATHOLIC HIGH SCHOOL Preliminary Examination Secondary 4 (O-Level Programme) PHYSICS 6091/02 Paper 2 Theory 15 September 2021 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work that you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, glue or correction fluid. Section A Answer all questions. Section B Answer all questions. 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 workings in a clear and orderly manner, as more marks are awarded for sound use of Physics than for correct answers. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For examiner’s use only: Section A / 50 Section B / 30 Total Marks / 80 Paper Type of Paper Marks Weighting 1 Multiple Choice 40 30 % 2 Theory 80 50 % 3 Practical 40 20 % This document consists of 20 printed pages. 50  s.f.  formula Section A

2 Section A Answer all the questions in this section. 1 A rock from space is travelling in a straight line at high speed when it enters the Earth’s atmosphere. Fig. 1.1 is the speed-time graph for the rock from time t = 0 to time t = 50 s. Fig. 1.1 (a) (i) On Fig. 1.1, mark with 1. a letter X, where the rock is moving with a constant speed, 2. a letter Y, where the rock has a non-uniform deceleration. [2] (ii) At time t = 25 s, the mass of the rock is 8.4 kg. Determine, at this instant, 1. the magnitude of the acceleration of the rock, acceleration = [2]

3 2. the magnitude of the resultant force on the rock. force = [1] (b) (i) Fig. 1.2 shows the rock at time t = 25 s. Fig. 1.2 1. On Fig. 1.2, draw and label an arrow to show the direction of the gravitational force F acting on the rock. [1] 2. Explain why the direction of travel of the rock changes as it travels through the Earth’s atmosphere. [2] (ii) State what happens to the rock at time t = 40 s. [1]

4 2 Fig. 2.1 shows a screwdriver of mass 64 g resting in equilibrium on a pivot. Fig. 2.1 (a) (i) Calculate the magnitude of the normal contact force from the pivot acting on the screwdriver. force = [1] (ii) A student suggested that the weight of the screwdriver and the normal contact force of the pivot acting on the screwdriver form an action-reaction pair. Explain why the student is wrong. [1] (b) (i) On Fig. 2.1, mark and label with a letter C, the centre of gravity of the screwdriver. [1] (ii) Explain why the screwdriver will not be in equilibrium if it is pivoted at a different point. [2]

5 3 A person whose weight is 500 N is standing on a platform with negligible weight as shown in Fig. 3.1. The platform is resting on a piston whose cross-sectional area is 2.0 × 10-2 m2. The piston causes a height of water h to be supported by the piston. The value of the atmospheric pressure is 1.0 × 105 Pa and the density of water is 1000 kg m-3. Fig. 3.1 (a) Calculate the value of h. h = [2] (b) The column on the left-hand side is no longer exposed to the atmosphere and it is sealed such that the top part of the column is a vacuum. State and explain how the value of h would change. [2] platform piston

6 4 Fig. 4.1 shows a black car going up a hill on a bright, sunny day. Fig. 4.1 (a) State (i) one way in which the car is gaining thermal energy, [1] (ii) one way in which the car is losing thermal energy. [1] (b) The car accelerates up the hill. In addition to the changes in the thermal energy of the car, there are other energy changes taking place. State the other energy changes that occur as the car moves up the hill. [2]

7 5 Fig. 5.1 shows an old coin displayed in a museum. Fig. 5.1 The coin is vertical and is supported by a stand. A mirror 0.17 m behind the coin ensures that the back of the coin can be seen by a visitor looking from the line P. M is a point on the coin. (a) On Fig. 5.1, (i) draw two rays of light from M to show how its image is produced, [2] (ii) label its image with a letter I. [1] (b) State the distance from point M on the coin to its image. distance = [1]

8 6 Fig. 6.1 shows a young boy lying on his back on the bottom of a swimming pool. He is holding his breath and his eyes are open. A red light is positioned on the ground at Q. At first the boy’s head is touching the pool wall. He notices that, as he slides away from the pool wall, his eye reaches a point P where he first sees the light at Q. Fig. 6.1 shows the boy in this position. Fig. 6.1 (a) On Fig. 6.1, draw the ray of light travelling from Q to P. [1] (b) (i) The critical angle is 49°. Calculate the refractive index of water. refractive index = [2] (ii) Hence, explain why the boy is unable to see the red light at Q when his eye is closer to the pool wall than when his eye is at point P. [2]

9 7 A large number of television sets in a shop are tuned to the same station. The television signal travels to some of the television sets via a satellite orbiting the Earth and to other television sets directly from a ground-based transmitter. (a) (i) Explain why only electromagnetic waves are used to transmit the television signal. [1] (ii) State the region of the electromagnetic spectrum used to transmit the television signal. [1] (iii) Suggest why satellites are sometimes used to transmit television signals instead of a ground-based transmitter. [1] (b) A salesman notices that the television signal sent via the satellite arrives 0.24 s later than the one sent directly from the ground-based transmitter. Calculate the additional distance travelled by the television signal from the satellite. distance = [2]

10 8 A positively charged plastic rod is placed just above a metal plate. The metal plate rests on an insulator and is connected to the earth by an earthing wire as shown in Fig. 8.1. Fig. 8.1 A student disconnects the earthing wire and then removes the positively charged rod. (a) State and explain the type of charge on the metal plate after the positively charged rod is removed. [2] (b) The experiment is repeated. This time the student removes the positively charged rod before removing the earthing wire. State and explain if the type of charge on the metal plate now would be different. [2] positively charged rod