2020 RI Prelims H2 Phy Paper 3 Sect B QP

This document consists of 10 printed pages. © Raffles Institution 9749/03 [Turn over Centre Number Index Number Name Class S3016 RAFFLES INSTITUTION 2020 Preliminary Examination PHYSICS Higher 2 Paper 3 Longer Structured Questions 9749/03 23 September 2020 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your index number, name and class in the spaces at the top of this page. Write in dark blue or black pen in the spaces provided in this booklet. You may use 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. Section A Answer all questions. Section B Answer one question only and circle the question number on the cover page. You are advised to spend one and half hours on Section A and half an hour on Section B. The number of marks is given in brackets [ ] at the end of each question or part question. *This booklet only contains Section B. For Examiner’s Use Section B (circle 1 question) 7 / 20 8 / 20 Deduction

2 © Raffles Institution 9749/03 Section B Answer one question from this Section in the spaces provided. 7 A metal cylinder that contains a fixed amount of a monatomic ideal gas is shown in Fig. 7.1. The cylinder is fitted with a piston that moves freely. Fi g. 7.1 Initially, the gas in the cylinder has a volume of 10.0 cm3 and a temperature of 27.0 C. Its initial pressure is the same as the atmospheric pressure of 1.00  105 Pa. (a) (i) Explain what is meant by an ideal gas. [1] (ii) Calculate the number of moles n of gas in the cylinder. n = mol [2] piston metal cylinder ideal gas

3 © Raffles Institution 9749/03 [Turn over (b) The gas in the cylinder undergoes a cycle of changes ABCA, where process AB: the gas is expanded at a constant temperature until its pressure decreases to 0.10  105 Pa. process BC: the gas is heated at a constant volume until it reaches atmospheric pressure again. process CA: the gas is compressed at a constant pressure until it returns to its initial state. Fig. 7.2 shows the p-V curves for two of the three processes. Fig. 7.2 (i) State the first law of thermodynamics, indicating the directions of all energy changes. [1] A C B p / 105 Pa V / cm3

4 © Raffles Institution 9749/03 (ii) With reference to the process AB, 1. state how this process can be achieved in practice, [1] 2. complete Fig. 7.2 by drawing the pV curve as accurately as possible. [2] (iii) With reference to the process BC, show that the heat supplied to the ga