Physics 9702/12 May/June 2021: question paper and mark scheme

Question

What is not a reasonable estimate of the physical property indicated? A 2 × 103 W for the power dissipated by the heating element of an electric kettle B 4 × 102 m3 for the volume of water in a swimming pool C 5 × 105 N s for the momentum of a lorry moving along a road D 6 × 102 N for the weight of a fully grown racehorse

Question

Which quantity could have units of N m V–1? A acceleration B charge C current D resistance

Question

An object is acted upon by two forces, 10 N in the vertical direction and 6 N at 40° to the vertical, as shown. 10 N 40 6N What is the resultant force acting on the object? A B C D 15 N 15 N 15 18 7.7 N 6.6 N 37 36

Question

An analogue ammeter with a range of 0–250 mA is connected into an electrical circuit. The diagram shows the ammeter’s display. 5 10 What is the reading on the ammeter? 0 A 76 mA B 165 mA C 183 mA D 190 mA

Question

Students take readings of the volume of a liquid using three different pieces of measuring equipment X, Y and Z. The true value of the volume of the liquid is V. The students’ results are shown. X Y Z number of number of number of readings readings readings 0 0 0 0 V volume 0 V volume 0 V volume How many pieces of equipment are precise and how many are accurate? number of precise number of accurate pieces of equipment pieces of equipment A 1 1 B 1 2 C 2 1 D 2 2

Question

Which graph shows the variation with time t of the velocity v of an object falling vertically downwards in a vacuum? A B v v 0 0 0 t 0 t C D v v 0 0 0 t 0 t

Question

A projectile is fired from point P with velocity V at an angle θ to the horizontal. It lands at point Q, a horizontal distance R from P. Air resistance is negligible. path of projectile V P Q horizontal R The acceleration of free fall is g. Which equation for R is correct? R = V sin θ cos θ 2 A g R = 2V sin θ cos θ 2 B g R = V sin θ cos θ 2 C 2g V 2g sin θ cos θ D R= 2

Question

A book of weight W is at rest on a table. A student attempts to state Newton’s third law of motion by saying that ‘action equals reaction’. book table W If the weight of the book is the ‘action’ force, what is the ‘reaction’ force? A the force W acting downwards on the Earth from the table B the force W acting upwards on the book from the table C the force W acting upwards on the Earth from the book D the force W acting upwards on the table from the floor

Question

Four balls are dropped at the same time from the top of a very tall tower. There is no wind blowing. Which ball hits the ground first? A B C D mass M mass 4M mass M mass 4M diameter D diameter D diameter 2D diameter 2D

Question

A nitrogen molecule P travelling at a speed of 320 m s–1 in a vacuum collides with a stationary nitrogen molecule Q. After the collision, P travels at a velocity of 180 m s–1 at an angle of 55° to its original path. Q travels in a direction at an angle of 34° to the initial path of P. 180 m s–1 P 320 m s–1 55 P Q 34 Q v before collision after collision Assume that there are no external forces acting on the molecules. What is the magnitude v of the velocity of Q after the collision? A 120 m s–1 B 140 m s–1 C 180 m s–1 D 260 m s–1

Question

A charged particle is placed in a uniform field of force. The direction of the force on the particle is opposite to the direction of the field. What is the field and what is the charge on the particle? field charge on particle A electric negative B electric positive C gravitational negative D gravitational positive

Question

A disc of radius r is acted upon by two opposite forces, each of magnitude F. The forces form a couple, as shown. F r F What is the torque of this couple? 1 A 2 Fr B Fr C 2Fr D 4Fr

Question

A uniform square sign of weight 40 N is suspended vertically from its top edge by a horizontal hinge, as shown. front view side view hinge hinge sign 0.80 m sign 0.80 m The hinge is not frictionless. When the sign is displaced from the vertical by an external force and then released, it does not return to the vertical position. The maximum torque exerted by the hinge on the sign is 6.0 N m. The sign is displaced by 90° so that it is horizontal and then gradually released. At which angle to the vertical does the sign hang after release? A 11° B 22° C 68° D 79°

Question

Each foot of an elephant has a circular cross-section with a circumference of 1.4 m. The elephant has a mass of 5400 kg. The elephant is standing still with all four feet on the ground. Assume the pressure under each foot is the same. What is the approximate pressure exerted on the ground by each of the elephant’s feet? A 8.7 kPa B 35 kPa C 85 kPa D 340 kPa

Question

A stone is falling vertically through the air at a constant (terminal) velocity. Which energy change is occurring? A gravitational potential energy to thermal energy B gravitational potential energy to kinetic energy of the stone C kinetic energy to gravitational potential energy of the stone D kinetic energy of the stone to thermal energy

Question

An object of weight 12 N rests on a platform on top of a container with two pistons, as shown. The container contains a fixed mass of gas, and the pistons are free to move. object platform piston piston plunger container The plunger is slowly pushed 4.0 cm to the right. As a result, the object slowly moves upwards a distance 0.50 cm. How much work is done on the object? A 0.060 J B 0.48 J C 6.0 J D 48 J

Question

A constant force F, acting on a car of mass m, moves the car up a slope through a distance s at constant velocity v. The angle of the slope to the horizontal is α. s F α The acceleration of free fall is g. gravitatio nal potential energy gained by car What is the ratio ? work done by force F mgs sinα mv mv 2 mg sinα A B C D Fv Fs 2Fs F

Question

What is the definition of power? A Power is the product of force and velocity. B Power is the product of force and work done per unit time. C Power is the product of force per unit time and velocity. D Power is the rate at which work is done.

Question

A steel bar of circular cross-section is under tension T, as shown. The diameter of the wide portion is double the diameter of the narrow portion. T T What is the value of stress in the wide portion ? stress in the narrow portion A 0.25 B 0.50 C 2.0 D 4.0

Question

Two guitar strings are stretched by tensile forces. String X is stretched by a tensile force F that causes an extension x. String Y is stretched by a tensile force 2F that causes an extension 2x. The strings obey Hooke’s law. strain energy in stretched string X What is the ratio ? strain energy in stretched string Y A 4 B 2 C 1 2 D 1 4

Question

Two lasers emit light in a vacuum. One laser emits red light and the other emits green light. Which property of the light from the two lasers must be different? A amplitude B frequency C intensity D speed

Question

Two particles in a progressive wave are a distance 10 cm apart. The two graphs show the variation with time t of the displacement d of the two particles. d d 0 0 0 t 0 t What could be represented by the two graphs? A particles in a longitudinal wave with a compression and the nearest rarefaction separated by 10 cm B particles in a longitudinal wave with a compression and the nearest rarefaction separated by 20 cm C particles in a transverse wave with a peak and the nearest trough separated by 20 cm D particles in a transverse wave with two adjacent peaks separated by 10 cm

Question

A sound wave is detected by a microphone that is connected to a cathode-ray oscilloscope (CRO). The screen of the CRO displays a waveform, as shown. The time-base is set to 20 μs div–1. What is the frequency of the sound wave? A 15 Hz B 15 000 Hz C 20 000 Hz D 30 000 Hz

Question

A person stands at the side of a straight railway track. A train moves towards the person and emits sound from its whistle. The person hears a sound of frequency 1690 Hz as the train approaches him. The person then hears sound of frequency 1500 Hz as the train moves away from him. The speed of sound in air is 340 m s–1. What is the speed of the train? A 20 m s–1 B 38 m s–1 C 41 m s–1 D 43 m s–1

Question

Which list shows electromagnetic waves in order of decreasing frequency? A gamma-rays → infrared → ultraviolet → radio waves B gamma-rays → ultraviolet → infrared → radio waves C radio waves → infrared → ultraviolet → gamma-rays D radio waves → ultraviolet → infrared → gamma-rays

Question

A pipe of length L is open at one end and closed at the other end. A loudspeaker is at the open end and emits a sound wave into the pipe. pipe L loudspeaker When a stationary wave is formed, there is an antinode at the open end of the pipe. Which wavelength of sound could be used to produce a stationary wave? A 2L B L C 4L D 2L 3 3

Question

Which diagram best shows how water waves diffract when they pass through a gap in a barrier? A B gap barrier C D

Question

In a two-source interference experiment, light of a single frequency is incident on a double slit. The light waves emerging from the slits are coherent. What is meant by coherent ? A The waves are in phase. B The waves have a constant phase difference. C The waves have the same amplitude. D The waves interfere constructively wherever they overlap.

Question

A parallel beam of light consists of light of wavelength 420 nm and light of wavelength 630 nm. The light is incident normally on a diffraction grating. The diffraction maxima for the two wavelengths overlap only at an angle of 31° from the direction of the incident light beam. What could be the line spacing of the diffraction grating? A 1.2 μm B 1.6 μm C 2.4 μm D 3.7 μm

Question

A positively charged particle P is in an electric field, as shown. Y X P Z The field lines (lines of force) are evenly spaced and parallel. Which statement is correct? A Moving P a small distance in any direction will not change the electric force on P. B Moving P a small distance in direction Y will increase the electric force on P. C Moving P a small distance in direction Z will increase the electric force on P. D Moving P a small distance in direction X will increase the electric force on P.

Question

The diagram shows two parallel metal plates P and Q, separated by a distance of 5.0 mm. There is a potential difference of 700 V between the plates. Plate Q is earthed. –700 V plate P 5.0 mm R plate Q 0V What is the magnitude and direction of the electric field at point R? A 1.4 × 102 N C–1 from P towards Q B 1.4 × 102 N C–1 from Q towards P C 1.4 × 105 N C–1 from P towards Q D 1.4 × 105 N C–1 from Q towards P

Question

A wedge-shaped metal conductor of length L, varying width and uniform thickness is connected to a cell, as shown. Y X L Which graph best shows how the average drift velocity v of electrons in the conductor varies with distance x from end X? A B C D v v v v 0 0 0 0 0 L 0 L 0 L 0 L x x x x

Question

The power output of an electrical supply is 2.4 kW at a potential difference (p.d.) of 240 V. The two wires between the supply and a kettle each have a resistance of 0.50 Ω, as shown. supply kettle 0.50 Ω 240 V 2.4 kW 0.50 Ω What is the power supplied to the kettle and what is the p.d. across the kettle? power / kW p.d. / V A 2.3 230 B 2.3 235 C 2.4 230 D 2.4 235

Question

The graph shows the variation with potential difference V of the current I in components X, Y and Z. I X Z Y 0 0 V Which row correctly identifies the components? metallic conductor at semiconductor filament constant temperature diode lamp A X Z Y B Y X Z C Y Z X D Z Y X

Question

A wire of resistance 9.55 Ω has a diameter of 0.280 mm. It is made of metal of resistivity 4.90 × 10–7 Ω m. What is the length of the wire? A 1.20 m B 4.80 m C 19.0 m D 76.0 m

Question

A cell of constant electromotive force (e.m.f.) but with internal resistance is connected to a fixed resistor R using a potentiometer. A voltmeter measures the potential difference (p.d.) between the terminals of the cell. Z V X R Which statement explains the change to the reading of the voltmeter as contact Z is moved towards end X of the potentiometer? A The voltmeter reading decreases because the current through the cell decreases. B The voltmeter reading decreases because the current through the cell increases. C The voltmeter reading increases because the current through the cell decreases. D The voltmeter reading increases because the current through the cell increases.

Question

A cell of electromotive force (e.m.f.) E and negligible internal resistance is connected to a circuit. The circuit has currents I1, I2 and I3, and potential differences V1, V2 and V3, as shown. E V2 I1 I2 V1 V3 I3 Which equation represents a statement of Kirchhoff’s first law? A I1 = I2 + I3 B I1 = I2 = I3 C E = V1 + V2 D V1 = V2 = V3

Question

Two resistors are connected in series with a 6.0 V power supply, as shown. +6.0 V R 12 k 0V What is the resistance of the variable resistor R to give a potential difference of 1.0 V across the 12 kΩ resistor? A 2.0 kΩ B 10 kΩ C 60 kΩ D 72 kΩ +

Question

A nucleus of magnesium decays into a nucleus X by emitting a β particle. The decay is represented by the equation shown. 23 12 Mg → P Q X + β 0 + 1 What are the values of P and Q? P Q A 22 11 B 22 13 C 23 11 D 23 13

Question

In β– decay, a neutron inside a nucleus changes to a proton. Which statement describes the quark composition of the nucleus during the decay? A The number of down quarks decreases by one. B The number of down quarks increases by one. C The number of down quarks stays the same. D The number of up quarks stays the same.