NJC H2 Physics Prelim P3 QP

[Turn over NATIONAL JUNIOR COLLEGE SENIOR HIGH 2 PRELIMINARY EXAM Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER PHYSICS Paper 3 Longer Structured Questions Candidate answers on the Question Paper. No Additional Materials are required. 9749/03 25 Aug 2023 2 hours READ THESE INSTRUCTION FIRST Write your subject class, registration number and name on all the work you hand in. 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. Section A Answers all questions. Section B Answer one question only. You are advised to spend one and a half hours on Section A and half an hour on Section B. 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 Section A 1 / 7 2 / 10 3 / 9 4 / 10 5 / 8 6 / 6 7 / 10 Section B 8 / 20 9 / 20 Total (80m) This document contains 28 printed pages and 4 blank pages.

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4 Section A 1 A bungee jumper of mass 60 kg is attached to an elastic rope which starts to stretch after a short time of free fall. The gravitational potential energy of the bungee jumper is 0 J when she has fallen through 40 m to the lowest point. (a) gravitational potential energy / kJ elastic potential energy / kJ kinetic energy / kJ top 0 0 half-way 2.6 bottom 0 Fig. 1.1 Fill up the missing energies at the top, bottom and half-way positions in Fig 1.1. Drag forces can be considered negligible. [2] (b) Show that the unstretched length of the elastic rope is 10 m. [2] (c) Determine at what extension will the kinetic energy of the bungee jumper be the highest. extension = ……………………….. m [3] [Total: 7]

5 [Turn over 2 Fig. 2.1 shows a small conducting sphere suspended from a long insulating thread between two metal plates M and M' that are 0.0500 m apart. The plates are connected to a  35.0 10 V battery. The sphere has a radius of 0.0025 m and a mass of 1.0 g. Fig. 2.1 The sphere is given an initial displacement such that the sphere touches M. It then moves rapidly to M', touches it, and returns rapidly to M again. This process repeats itself. (a) State and explain why an initial displacement to touch one of the plates is necessary for the process to start. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………