2021 RI Promo Sect A QP

© Raffles Institution 9749 RAFFLES INSTITUTION 2021 YEAR 5 PROMOTIONAL EXAMINATION 30 September 2021 Time: 2 hr 30 min H2 PHYSICS RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION Section A INSTRUCTIONS TO CANDIDATES There are 3 sections in this paper. Section A consists of 15 multiple-choice questions. For each question, four suggested answers are given. You are to choose the most appropriate one and shade your answer on the OMR form, using a soft pencil. You are advised to attempt Section A first. The OMR form will be collected at the end of the first 30 minutes. Section B consists of 5 structured questions. You ar e to write your answers in the spaces provided. Section C consists of 2 longer structured questi ons. You are to write your answers in the spaces provided. Attempt ALL questions in Sections A, B and C. This document consists of 8 printed pages.

2 © Raffles Institution 9749 [Turn over   Data speed of light in free space c  3.00 × 108 m s1 permeability of free space 0  4   107 H m1 permittivity of free space 0  8.85 × 10 12 F m1  (1/(36 )) × 109 F m1 elementary charge e  1.60 × 10 19 C the Planck constant h  6.63 × 10 34 J s unified atomic mass constant u  1.66 × 10 27 kg rest mass of electron me  9.11 × 10 31 kg rest mass of proton mp  1.67 × 10 27 kg molar gas constant R  8.31 J K 1 mol1 the Avogadro constant NA  6.02 × 10 23 mol1 the Boltzmann constant k  1.38 × 10 23 J K1 gravitational constant G  6.67 × 10 11 N m2 kg2 acceleration of free fall g  9.81 m s 2   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 [Turn over   Section A (15 marks) 1 The resistive force F acting on a sphere of radius r travelling with speed v through a liquid is given by the equation 6Fr v  where  is a constant. What are the SI units of  ? A 11kg m s B 21kg m s  C 12kg m s D 13kg s 2 Two lengths X and Y are measured to be  51.0 0.1 cm and  49.0 0.1 cm respectively. Which of the following quantities has the largest percentage uncertainty? A X Y B X Y C XY D X Y 3 Jack and Jill are standing 15 m apart on level ground when Jack throws a ball with speed u at an angle above the horizontal towards Jill. At the same time when Jack throws the ball , Jill runs towards it with a speed of 18.9 m s and catches the ball 0.49 s after it is thrown. The ball is thrown and caught at the same height above the ground. What is the speed u of the ball? A 111 m s B 122 m s C 131 m s D 140 m s

4 © Raffles Institution 9749 [Turn over   4 A piece of rope with a maximum allowable tens ion of 30 N is used to lift a 2.0 kg crate containing a 0.30 kg present. The crate is accelerated upwards at an increasing rate until the rope breaks. What is the force that the present exerts on the crate just before the rope breaks? A 3.9 N B 4.5 N C 9.5 N D 26 N 5 A projectile of mass 2 m is launched at an angle to the ground with a speed of 20 m s –1. When the projectile is at the peak of its traj ectory, 9.0 m above the ground, it explodes into two pieces, X and Y, each of equal mass m. If Y has a speed of 40 m s –1 horizontally to the right immediately after the explosion, what is the speed of X immediately after the explosion? Ignore the effects of air resistance. A 10 m s B 110 m s C 125 m s D 140 m s crate rope present 40 m s–1 20 m s–1 X Y ground 9.0 m

5 © Raffles Institution 9749 [Turn over   6 A 2.0 m beam with a non-uniform mass distribution is supported at its ends P and Q by two identical vertical springs of unstretched length 4.0 cm. When the beam is in equilibrium, the lengths of each spring are 6.5 cm and 9.0 cm as shown. What is the distance between the beam’s centre of gravity and end P? A 1.0 m B 1.2 m C 1.3 m D 1.4 m 7 A block is at rest on a slope. Point G represents the centre of gravity of the wooden block. Which of the following shows the direction of the force the slope exerts on the block? A B C D 6.5 cm 9.0 cm P Q beam springs slope block G G G G G

6 © Raffles Institution 9749 [Turn over   8 Two objects P and Q of masses m and 2 m respectively are initially at rest on a smooth, horizontal surface. If the same force acts on each of them for the same duration, the ratio gain in kinetic energy by P gain in kinetic energy by Q is A 0.25 B 0.50 C 1.0 D 2.0 9 A pendulum of length L and mass m is displaced at an angular displacement max from the vertical as shown. The pendulum is released. Which of the following graph best repres ents the variation with angular position  of the tension T in the string? A B C D T  mg maxmax T  mg maxmax T  mg maxmax T  mg maxmax max L

7 © Raffles Institution 9749 [Turn over   10 Which row describes the effect of atmospheric drag on a satellite’s orbit? orbital speed orbital radius total ener gy A increases increases increases B increases decreases decreases C decreases increases increases D decreases decreases decreases 11 A 1.0 kg mass is attached to a horizontal spring on a smooth table. The mass is then displaced horizontally from its equilibrium position by 0.10 m and released from rest. The mass next comes to rest again after 0.50 s. What is the maximum speed of the mass? A 10.31 m s B 10.39 m s C 10.63 m s D 10.99 m s 12 A 50 g mass is suspended from one end of a light spring of force constant 125 N m