Raffles Institution 2019 Y4 FE Sections A and B

1 Section A [30 marks] Four possible answers A, B, C and D are given for each question. Choose the most appropriate answer and shade your answers in pencil on the OTAS answer sheet provided. 1 Which option consists of a pair of SI base unit? A ampere joule B newton second C kilogram kelvin D metre coulomb 2 A box is dropped from a tall building. As the box falls, air resistance has a noticeable effect on its motion. Graph 1 Graph 2 Graph 3 How many graph(s) correctly describe(s) the motion of the box from time 0 s to time t? A 0 B 1 C 2 D 3 3 An object is moving with an initial velocity of 6.0 m s−1 to the right when it undergoes acceleration for a duration of 6.0 s as shown. Take displacement to the right as positive. What is the velocity of the object after 6.0 s? A −2.0 m s−1 B 2.0 m s−1 C 4.0 m s−1 D 8.0 m s−1 1.0 −4.0 a / m s−2 t / s 0 1.0 2.0 3.0 4.0 5.0 6.0 displacement / m time / s 0 t acceleration / m s−2 time / s 0 t velocity / m s−1 time / s 0 t

2 4 Forces of 3.0 N and 6.0 N act at a point. Which vector diagram shows a resultant of 6.0 N? A B C D 5 When a metal ball of weight W is placed inside a beaker of water, the newton-balance reads X. When the immersed metal ball is suspended by a spring-balance, the newton-balance reads Y. What is the reading of the spring balance? A X − W B X − Y C Y − W D Y spring-balance newton-balance Y X newton-balance metal ball in a beaker of water 3.0 N 6.0 N 3.0 N 6.0 N 3.0 N 6.0 N 3.0 N 6.0 N

3 6 A clown on a unicycle accelerates to the right as shown. What is the direction of the frictional force acting on the wheel? A B C D 7 An L-shaped bar of uniform density and uniform cross-sectional area is hung on a frictionless pin P at its right-angle corner as shown. The lengths of the sides are x and 2x respectively. What is the angle θ that the shorter arm makes with the vertical? A 14° B 27° C 63° D 76° 8 An object of mass 2.0 kg is falling at a speed of 3.00 m s -1 at one particular instant. It experiences an average resistive force of 1.0 N as it falls . What is the gain in kinetic energy of the object after it falls a further distance of 15.0 m? A 279 J B 288 J C 294 J D 303 J 9 A scientist is shown a collection of electric cars. He is provided with only four measuring instruments and tasked to determine which of the cars has the greatest power. Which instrument will be the least useful to the scientist? A industrial weighing scale B speedometer C stopwatch D voltmeter P θ 2x x acceleration wheel road

4 10 Which information cannot be determined from the displacement-time graph of a wave? A amplitude B frequency C period D wavelength 11 A ship emits an ultrasound of wavelength 7.10 × 10-2 m to determine the depth of the sea. The time interval between emitting the ultrasound and detecting the echo is 38500 times the period of the ultrasound. What is the depth of the sea? A 1370 m B 2730 m C 5470 m D 5.42 × 105 m 12 Which factor will not affect the rate of evaporation? A depth of liquid B humidity of surrounding air C temperature of liquid D pressure of surrounding air 13 A student mixes 0.200 kg of water at 0 oC with ice at −10.0 oC at standard atmospheric pressure. specific heat capacity of water, cw = 4200 J/kg.oC specific heat capacity of ice, ci = 2100 J/kg.oC specific heat capacity of steam, cs = 2000 J/kg.oC specific latent heat of fusion of ice, lf = 3.34 × 105 J/kg specific latent heat of vaporization of water, lv = 2.26 × 106 J/kg What is the minimum mass of ice needed to turn the water into ice? A 0.200 kg B 1.59 kg C 2.00 kg D 3.18 kg

5 14 A positively charged ball A attracts ball B. Which statement(s) about ball B is/are possible? 1. It has a smaller net positive charge than ball A. 2. It is neutral. 3. It is earthed. A statement 2 only B statement 3 only C statements 2 and 3 only D All the statements are possible. 15 The diagram shows two spheres X and Y of unknown materials touching each other. Sphere X is earthed and sphere Y is negatively charged. The earth connection is removed from sphere X and then the spheres are separated. Sphere X is found to be positively charged and sphere Y remains negatively charged. Which of the following describes the nature of the materials of the spheres? sphere X sphere Y A insulator insulator B insulator conductor C conductor insulator D conductor conductor 16 In the circuit below, n charge carriers pass through point P in time t. Each charge carrier has charge q. What is the current in the circuit? A q t B nq t C qt n D nqt sphere Y, negatively charged sphere X, earthed P

6 17 When the potential difference across an ohmic conductor is V, its resistance is R. What is the resistance of the ohmic conductor when the potential difference across it is 2 V ? A 2 R B R C 2R D 4R 18 The cells in circuits X, Y and Z have the same e.m.f. and zero internal resistance. The resistors in the circuits have the same resistance. Which of the following gives the current through the cells in increasing order? lowest current  highest current A X Z Y B Z Y X C Y Z X D Y X Z 19 What is the effective resistance of the circuit below? A 1.0 Ω B 2.0 Ω C 4.0 Ω D 11 Ω circuit X circuit Y circuit Z 2.0 Ω 3.0 Ω 6.0 Ω

7 20 Resistors of resistances R1 and R2 are connected in a circuit as shown below. When switch S is opened, the ammeter reads 1.5 A and the voltmeter reads 9.0 V. When switch S is closed, the ammeter reads 3.0 A and the voltmeter reads 6.0 V. What are resistances R1 and R2? R1 / Ω R2 / Ω A 2.0 6.0 B 3.0 6.0 C 2.0 8.0 D 3.0 8.0 21 The table below shows the cost of using solar energy to power a 100 W heater for 24 hours each day. price of solar panel and installation maintenance fee per year $ 2500 $ 100 The estimated cost of purchasing electricity from an electrical retailer is $0.40 per kWh for the next 20 years. What is the minimum number of years before the cost of using solar energy is totally recovered? A 5 years B 10 years C 15 years D 20 years 22 A 10 Ω resistor and a 20 Ω resistor are connected in parallel to a battery. What is the ratio of the power dissipated by the 10 Ω resistor to the power dissipated by the 20 Ω resistor? A 1 : 2 B 1 : 4 C 2 : 1 D 4 : 1 2 Ω R1 R2 S

8 23 The diagram below shows the magnetic field lines due to two current -carrying wires that are perpendicular to the plane of the paper. Which set of compasses shows the correct directions of the needles at positions 1, 2 and 3? position 1 position 2 position 3 A B C D 24 An iron rod and a steel rod are placed inside a solenoid that is connected to a d.c. supply. Which diagram shows the side view of the rods when the circuit is switched on for a while, before it is switched off again? A B C D 1 2 3 iron rod steel rod side view front view on off again on off again on off again on off again on off again

9 25 The diagram shows a current-carry wire in a uniform magnetic field. Which modification will increase the magnetic force acting on the wire? A increase the strength of the magnetic field B increase the current C reverse the direction of the magnetic fiel