2022 SJI Phy Prelims P2 SectA

ST JOSEPH’S INSTITUTION PRELIMINARY EXAMINATION 2022 (YEAR 4) CANDIDATE NAME CLASS INDEX NUMBER PHYSICS Paper 2 6091/02 12 September 2022 1 hour 45 minutes (08:00 – 09:45) READ THESE INSTRUCTIONS FIRST Write your name, class and index number on the cover page of this Question Paper and all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue or correction fluid. Section A Answer all questions on the Question paper. Section B Answer all questions. Question 12 has a choice of parts to answer. Candidates are reminded that all quantitative answers should include appropriate units. Candidates are advised to show formulae and all their working in a clear and orderly manner, as mor e marks are awarded for sound use of Physics than for correct answers. The number of marks is given in brackets [ ] at the end of each question or part question. Section A Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 For Examiner’s Use Section A / 50 Section B / 30 Total / 80 This document consists of 24 printed pages including this cover page

2 Section A (50 marks) Answer all questions in this section. 1 Fig. 1.1 shows how the speed of a rocket SpaceX varies with time as it enter s the gravitational field of a new P lanet Y with negligible atmosphere. SpaceX has a total mass of 1.8 x 106 kg. Once it enters the atmosphere of Planet Y, it undergoes free fall for 8.0 s before its engine fires a continuous thrust to bring it to a gentle upright landing on the surface of Planet Y. Fig 1.1 (a) Calculate the weight of Space X on Planet Y. weight = ……………………..[2]

3 (b) At 8.0 s, significant amount of liquid Oxygen fuel undergoes combustion in the rocket engine to produce a constant thrust,T to decrease rocket’s speed of descent. (i) On Fig. 1.2, d raw and label all the forces acting on S paceX during its descent. You may ignore air resistance. [1] Fig. 1.2 (ii) Hence, calculate the magnitude of the thrust, T. T = ………………….. [2] (iii) With reference to the forces acting on SpaceX, explain why the deceleration from t = 8.0 s to t = 28.0 s increases in reality. Assume that the thrust produced by the engine is uniform throughout the descent. …………………………………………………………………………………… …………………………………………………………………………………… …………………………………………………………………………………[1]

4 2 A man in a hot air balloon drops a ping pong ball out of the hot air balloon as the balloon accelerates upwards at 2.0 m/s 2. The speed of the balloon is 2.0 m/s at the moment the ping pong ball is released. Fig. 2.1 shows how the velocities of the hot air balloon and the