2022 RI Prelims H2 Phy Paper 2 QP

This document consists of 24 printed pages. © Raffles Institution 9749/02 [Turn over Centre Number Index Number Name Class S3016 RAFFLES INSTITUTION 2022 Preliminary Examination PHYSICS Higher 2 Paper 2 Structured Questions 9749/02 12 September 2022 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. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 9 2 / 5 3 / 8 4 / 10 5 / 7 6 / 12 7 / 7 8 / 22 Deduction Total / 80

2 © Raffles Institution 9749/02 [Turn over Data speed of light in free space c  81 3.00 10 m s   permeability of free space 0  71 41 0 H m   permittivity of free space 0  12 18.85 10 F m    9113 6 1 0 F m  elementary charge e  191.60 10 C the Planck constant h  34 6.63 10 J s   unified atomic mass constant u  27 1.66 10 kg   rest mass of electron me  31 9.11 10 kg   rest mass of proton mp  27 1.67 10 kg   molar gas constant R  1 18.31 J K mol   the Avogadro constant NA  23 16.02 10 mol  the Boltzmann constant k  23 11.38 10 J K   gravitational constant G  11 226.67 10 N m kg   acceleration of free fall g  29.81 m s Formulae uniformly accelerated motion s  21 2ut at 2v  2 2ua s work done on / by a gas W  p V hydrostatic pressure p  ρgh gravitational potential   Gm r temperature T/K  / C 273.15T  pressure of an ideal gas p  21 3 Nm cV mean translational kinetic energy of an ideal gas molecule E  3 2 kT displacement of particle in s.h.m. x  0 sinx t velocity of particle in s.h.m. v  0 cosvt  22 0x x  electric current I  Anvq resistors in series R  12 RR  resistors in parallel 1/ R  1211 RR  electric potential V  4 Q r alternating current/voltage x  0 sinx t magnetic flux density due to a long straight wire B  0 2 d   I magnetic flux density due to a flat circular coil B  0 2 N r  I magnetic flux density due to a long solenoid B  0n I radioactive decay x  0 expxt  decay constant   12ln2 t

3 © Raffles Institution 9749/02 [Turn over Answer all the questions in the spaces provided. 1 Particle A of mass 9 m and particle B of mass m travel towards each other along a smooth horizontal surface in a straight line and colli de head-on. The initial speed of particle A before the collision is u. In Fig. 1.1, the variation with time t of momentum p is shown from 0t  to 3tT for particle A and from 0t  to tT for particle B. Fig. 1.1 particle A particle B 9mu p 0 T t 2T –3mu 3T

4 © Raffles Institution 9749/02 [Turn over (a) (i) On Fig. 1.1, draw the variation with t of p from tT to 3tT for particle B. [1] (ii) Explain how the principle of conservation of momentum is used to complete the graph in (a)(i). [2] (b) Explain, with appropriate working, whether the collision between particles A and B is elastic. [3] (c) Using Fig. 1.1, explain how the graphs are co nsistent with Newton’s third law of motion during the collision. [3]

5 © Raffles Institution 9749/02 [Turn over 2 A uniform square box with sides 0.80 m and mass 2.0 kg is at rest on the ground. One end of a light rope is attached to the box and the other end is attached to the wheel of a motor. The motor applies a constant clockwise torque of 5.0 N m on the wheel of radius 0.20 m. At the instant shown in Fig. 2.1, t he rope is taut and it makes an angle of 20  with the vertical side of the box. The system remains in equilibrium. Fig. 2.1 (a) Calculate the tension in the rope. tension = N [1] (b) Point M is the mid-point at the base of the box as shown in Fig. 2.1. By taking moments about point M, determine the horizontal distance d between M and the point at which the contact force by the ground acts on the box. d = m [3] motor ground box rope 0.80 m 0.80 m M

6 © Raffles Institution 9749/02 [Turn over (c) The motor is shifted to the right such that  increases. The torque applied by the motor remains constant. Without any further calculations, explain why there is a maximum value of  for which equilibrium can be maintained. [1]

7 © Raffles Institution 9749/02 [Turn over 3 A bob of mass 1.5 kg is attached to a string of negligible mass and of length 25.0 cm. The other end of the string is fixed to point X of an inverted “L” structure of arm length d. The structure is fixed to the centre of a rotating disc of radius 8.0 cm. When the disc rotates with an angular velocity  , the string makes at an angle  to the vertical as shown in Fig. 3.1. Fig. 3.1 (a) A point on the circumference of the rotating disc has a speed of 124.0 cm s . Determine  .  = rad s1 [1] (b) (i) Determine the tension in the string for 30  . tension = N [2]  X d rotating disc bob inverted “L” structure string

8 © Raffles Institution 9749/02 [Turn over (ii) Calculate d. d = m [3] (c) A student states that as the angular velocity of the disc increases,  increases but  will always be smaller than 90. Comment on the validity of the statement made by the student. [2]

9 © Raffles Institution 9749/02 [Turn over 4 (a) Explain why gravitational potential is always negative whereas electric potential can have positive and negative values, given that both potentials are zero at infinity. [3]

10 © Raffles Institution 9749/02 [Turn over (b) Fig. 4.1 shows how the gravitational potential  from the surface of a planet varies with distance r from the centre of the planet. Fig. 4.1 -20.0 -18.0 -16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0