MI 2024 PU3 H2 PHYSICS PRELIM P3B QP

Class Adm No Candidate Name: This document consists of 7 printed pages and 1 blank page. [Turn over 2024 Preliminary Examination Pre-University 3 H2 PHYSICS 9749/03 Paper 3 Longer Structured Question Section B Booklet 16 September Candidates answer on the Question Paper. 2 hours No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Do not turn over this page until you are told to do so. Write your full name, class and Adm number 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 an HB pencil for any diagrams, graphs or rough working. 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. 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. For Examiner’s Use Section B (Circle 1 question) 7 / 20 8 / 20 Presentation

2 Section B Answer ONE question from this Section in the spaces provided. 7 (a) Explain what are meant by the moment of a force and the torque of a couple. Distinguish between the two terms. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………………………………………………………………………………………….. [3] (b) One type of weighing machine, known as a steelyard, is illustrated in Fig. 7.1 Fig. 7.1 The 12 N and 2.5 N sliding weights can be moved independently along the light rigid rod. With no load on the hook and the sliding weights at the zero mark on the rigid rod, the rod is horizontal. The hook is 4.8 cm from the pivot. (i) Explain why the light rigid rod can remain horizontal with no load on the hook. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………[1] light rigid rod zero mark

3 [Turn over (ii) Explain why the perpendicular distance from the hook to the pivot is deliberately kept shorter compared to the length of the rigid rod. ………………………………………………………………………………………..…… …………………………………………………………………………………………..… …………………………………………………………………………………………….. …………………………………………………………………………………….…… [2] (iii) A sack of flour is suspended from the hook. In order to return the light rigid rod to the horizontal position, the 12 N sliding weight is moved 84 cm along the rod and the 2.5 N sliding weight is moved 72 cm. Calculate the mass of the sack of flour.