Kinetic particle model of matter — Paper 4 · IGCSE Sciences - Co-ordinated (Double) 0654

2 (a) A student plans an experiment to calculate the specific heat capacity of water by heating some water in a kettle. • She measures 1.2 kg of water into an electric kettle. • The initial temperature of the water is 18 °C. • She switches on the kettle and heats the water for 60 seconds. • The final temperature of the water is 49 °C. • The energy given to the water by the kettle in 60 seconds is 156 000 J. (i) Calculate the specific heat capacity of water. State the formula you use and show your working. formula working specific heat capacity = … J/kg °C [3] (ii) The kettle is supplied with 3000 joules of energy each second. The water in the kettle only gains 2600 joules of thermal energy each second. Calculate the efficiency of the kettle. State the formula you use and show your working. formula working efficiency = … % [2] (b) A kettle is switched on and the water reaches its boiling point. It starts to boil and the kettle remains switched on. Explain in terms of molecules what happens to the thermal energy supplied after the water starts to boil. … … … [2]

7 marks

Mark scheme: 2(a)(i) temperature change = 31 °C ; E/m∆θ / 156 000 / 1.2 × 31 ; = 4190 / 4194 (J / Kg °C) ; 3 2(a)(ii) efficiency = useful energy out / energy in × 100 / 2600 / 3000 × 100 ; = 87(%) ; 2 2(b) latent heat (of vaporisation) required ; as energy to break bonds / to overcome attractive forces ; between molecules / intermolecular bonds ; to increase potential energy of the molecules ; 2

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7 (a) Fig. 7.1 shows a speed-time graph for a car over a period of 50 seconds. BB CC 4 3 speed m / s 2 1 A DD EE 0 0 10 20 30 40 50 time / s Fig. 7.1 (i) State the maximum speed reached by the car. … m / s [1] (ii) Calculate the total distance travelled by the car. Show your working. distance = … m [2] (iii) Show that the acceleration of the car during the first ten seconds is 0.4 m / s2. [1] (iv) The mass of the car is 950 kg. Calculate the force needed to produce an acceleration of 0.4 m / s2. State the formula you use and show your working. formula working force = … N [2] (b) The temperature of the air in car tyres increases during a journey. (i) Describe what happens to the motion of the air particles as the air warms up. … … [1] (ii) When the temperature of the air in the tyres increases, the pressure in the tyres increases. Explain in terms of the motion of the air particles why the pressure increases. … … … [2] (c) Relays are needed in many electrical circuits used in machines. Fig. 7.2 shows a simple relay circuit. contacts high-voltage pivot circuit soft iron soft iron coil low-voltage circuit Fig. 7.2 (i) Describe how a small current flowing in a low-voltage circuit is able to turn on the high-voltage circuit. … … … … … [3] (ii) Suggest how the use of a relay in a high-voltage circuit protects the person operating a machine. … … [1]

13 marks

Mark scheme: 7(a)(i) 4 (m / s) ; 1 7(a)(ii) area under graph / working ; 20 + 20 + 50 = 90 (m) ; 2 7(a)(iii) working ; e.g. correct substitution into formula such as 4 / 10 ; 1 7(a)(iv) force = mass × acceleration / 950 × 0.4 ; 380 (N) ; 2 7(b)(i) move faster ; 1 7(b)(ii) more frequent collisions / collide at greater speed, with tyre wall ; more force exerted on tyre walls ; 2 7(c)(i) current in low voltage circuit creates magnetic field (around solenoid) ; soft iron attracted (to magnet / solenoid) ; contacts in high voltage circuit close ; 3 7(c)(ii) so that humans, are not exposed to the high voltage circuit / operate low voltage switching circuit / owtte ; 1

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6 (a) Fig. 6.1 shows the information label found on the back of a microwave oven. Serial number 1234567 240 V 0.9 kW 2500 MHz Fig. 6.1 (i) State the frequency of the microwaves used in the oven. … [1] (ii) State the power of the oven. … [1] (b) Infra-red radiation may also be used to heat food. State whether, compared with microwave radiation, infra-red radiation has a higher, lower or the same value of wavelength, … speed in a vacuum. … [1] (c) Some water is heated in the microwave oven for five minutes. Fig. 6.2 shows how the temperature of the water changes with time. 100 temperature / ºC 50 0 0 1 2 3 4 5 time / minutes Fig. 6.2 (i) Describe what happens to the water molecules during the first two minutes. … … [1] (ii) Explain, in terms of molecules, why the temperature of the water remains unchanged between two and five minutes. … … … [2]

6 marks

Mark scheme: 6(a)(i) 2500 MHz ; 1 6(a)(ii) 0.9 kW ; 1 6(b) lower wavelength same speed ; 1 6(c)(i) water molecules gain kinetic energy / move faster ; 1 6(c)(ii) latent heat of vaporisation / energy used to increase potential energy of the molecules ; to break bonds between molecules / to overcome attractive forces between molecules ; no change in kinetic energy so no increase in temperature ; max 2

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9 (a) A boy riding his bicycle is cooled by sweating. Describe, in terms of molecules, how sweating cools his body by evaporation. … … … … … [3] (b) Fig. 9.1 shows a car behind a bicycle at night. Fig. 9.1 A reflector on the back of the bicycle is made from many small red plastic prisms, one of which is shown in Fig. 9.2. A ray of light from the headlamp of the car enters the prism. ray of light from the headlamp of the following car red plastic prism Fig. 9.2 Total internal reflection occurs within the prism. On Fig. 9.2, complete the path taken by the ray of light until it emerges from the prism. [2] (c) The bicycle has a lamp powered by a small generator. The generator turns as the boy pedals and the lamp lights up. Fig. 9.3 shows a simple version of the generator. axle magnet magnet N S slip ring coil brush lamp Fig. 9.3 Describe how the rotating coil causes the lamp to light. … … … … … … [3] (d) The generator produces an alternating voltage. Fig. 9.4 shows how the output voltage of the bicycle generator changes with time. 6.0 4.0 2.0 voltage / V 0 time / s 0.02 0.04 0.06 0.08 0.10 –2.0 –4.0 –6.0 Fig. 9.4 (i) Calculate the frequency of the alternating voltage. Show your working. frequency = … Hz [1] (ii) State the amplitude of the alternating voltage. amplitude = … V [1] (e) A different bicycle has a front lamp, A, and a rear lamp, B, powered by the same battery. Fig. 9.5 shows how the lamps are connected. 12 V A B Fig. 9.5 (i) State the name given to this arrangement of lamps in a circuit. … [1] (ii) Lamp A has a resistance of 5 Ω. The battery has a voltage of 12 V. Calculate the current flowing through lamp A when the switch is closed. State the formula you use and show your working. formula working current = … A [2] (iii) Lamp B has a resistance of 10 Ω. Calculate the combined resistance of the two lamps in this circuit. Show your working. resistance = … Ω [2]

15 marks

Mark scheme: 9(a) fastest moving / most energetic molecules escape ; remainder are slower / have less energy ; energy used taken from surroundings / molecules gain energy from body ; 3 9(b) first 90° reflection correct ; second 90° reflection correct ; 2 9(c) rotation of coil, cuts magnetic field / experiences changing magnetic field ; induces an emf ; current flows through lamp / pd across lamp causes lamp to light ; 3 9(d)(i) frequency = 25 (Hz) ; 1 Question Answer Marks 9(d)(ii) amplitude = 5 (V) ; 1 9(e)(i) parallel ; 1 9(e)(ii) I = V / R or 12 / 5 ; 2.4 (A) ; 2 9(e)(iii) 1 2 1 2 T R R R R R = + or R = 10 / 3 (Ω) ; = 3.3 (Ω) ; 2

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10 (a) Fig. 10.1 shows the speed-time graph for the journey of a bus along a road for 80 seconds. 10 9 8 7 6 speed 5 m / s 4 3 2 1 0 0 10 20 30 40 50 60 70 80 time / s Fig. 10.1 (i) Calculate the distance travelled by the bus in 80 seconds. Show your working. distance = … m [3] (ii) The mass of the bus is 8000 kg. Calculate the maximum kinetic energy of the bus during the journey. State the formula you use and show your working. formula working kinetic energy = … J [3] (b) The bus has four wheels. Each wheel has a tyre inflated with air. After a long journey, the tyres are hot and the air pressure in the tyres has increased. (i) Describe how the air molecules in a tyre exert a pressure on the wall of the tyre. … … … [2] (ii) Explain, in terms of molecules, why the pressure of the air in the tyres increases when the temperature increases. … … … [2] (c) The bus has two headlights, L1 and L2. The lamp inside headlight L1 is connected in parallel with the lamp inside headlight L2 across a 12 V battery. Fig. 10.2 shows the circuit diagram for this arrangement. 12 V L1 L2 Fig. 10.2 (i) A current of 3.0 A flows through each lamp for 80 seconds. Calculate the total charge that flows through the two lamps. State the formula you use, show your working and state the unit of your answer. formula working charge = … unit … [3] (ii) The resistance of each lamp is 4.0 Ω. Calculate the combined resistance of the two lamps connected in parallel. Show your working. resistance = … Ω [2] (d) Some of the bodywork on the bus is made from iron. Other parts are made from steel. Both iron and steel are magnetic. Describe one difference between the magnetic properties of iron and the magnetic properties of steel. … … [1]

16 marks

Mark scheme: 10(a)(i) evidence of area under graph ; = 160 + 240 + 75 ; 475 (m) ; 3 10(a)(ii) max speed = 8 m / s ; KE = ½ m v2 OR ½ × 8000 × 8 × 8 ; = 256 000 (J) ; 3 10(b)(i) particles collide with tyre / walls / it ; exert a force (on the tyre wall) ; 2 10(b)(ii) particles are moving faster / more (kinetic) energy ; greater rate of collision / more energetic collisions ; more force exerted (on tyre walls) ; max 2 10(c)(i) Q=It OR 3 × 80 OR 240 ; 2 × 240 OR 480 ; C ; 3 10(c)(ii) correct formula / substitution / explanation ; 2.0 (Ω) ; 2 10(d) iron magnetises quickly / steel magnetises slowly / iron loses magnetism quickly / steel loses magnetism slowly ; 1

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12 (a) An electric cooker connected to a mains supply of 240 V has a power input of 6000 W. (i) Show that the current that flows is 25 A. State the formula you use and show your working. formula working [2] (ii) The cooker has its own circuit breaker. Explain why a circuit breaker rated at 20 A must not be used in the cooker circuit. … … … … [2] (b) Fig. 12.1 shows some water being heated in a saucepan on the hotplate of the cooker. water saucepan hotplate not to scale Fig. 12.1 The weight of the saucepan and water is 25 N. The area of the saucepan in contact with the cooker hotplate is 300 cm2. (i) Calculate the area of the saucepan in contact with the hotplate in m2. area = … m2 [1] (ii) Calculate the pressure exerted by the saucepan on the surface of the hotplate in Pa. State the formula you use and show your working. formula working pressure = … Pa [2] (c) Fig. 12.2 shows a graph of the temperature of the water as it is heated for 1000 s. 110 100 90 80 70 60 temperature / °C 50 40 30 20 10 0 0 100 200 300 400 500 600 700 800 900 1000 time / s Fig. 12.2 (i) The mass of the heated water is 1.5 kg. The specific heat capacity of water is 4200 J / (kg °C). Calculate the energy required to heat the water to 100 °C. State the formula you use and show your working. formula working energy = … J [3] (ii) Before the water boils, some of the water evaporates. State two ways in which boiling differs from evaporation. 1 … … 2 … … [2]

12 marks

Mark scheme: 12(a)(i) P V = I ; = 6000 240 ; 2 12(a)(ii) breaker would trip at working current ; breaking current should be more than current rating of device OR 20A < 25A / working current ; 2 12(b)(i) 0.03 (m2) ; 1 12(b)(ii) F P A = OR 25 0.03 ; = 830 (Pa) ; 2 12(c)(i) temp rise = 80°C ; E = m c ∆T OR 1.5 × 4200 × 80 ; = 504 000 (J) ; 3 Question Answer Marks 12(c)(ii) evaporation can occur at any temperature / boiling only happens at the boiling point ; evaporation happens only at the surface / boiling happens throughout the liquid ; boiling takes energy in to occur / evaporation lets only the molecules with the highest kinetic energy out ; evaporation can occur using the internal energy of the system / boiling requires an external source of heat ; evaporation produces cooling / boiling does not produce cooling ; evaporation is a slow process / boiling is a rapid process ; max 2

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6 (a) X-rays and γ-rays are both used in hospitals. They are both examples of ionising radiation. Before using an X-ray machine, the doctor moves and stands behind a lead screen. (i) Describe how X-rays are a hazard to living things. … … [1] (ii) Suggest why the screen is made of lead. … … [1] (b) (i) State, in terms of waves, the meaning of the term frequency. … … [1] (ii) The speed of all electromagnetic waves in vacuo is 3 × 108 m / s. X-rays have a wavelength of 5 nm. (1 nm = 10−9 m). Calculate the frequency of X-rays. State the formula you use and show your working. formula working frequency = … Hz [2] (c) Fig. 6.1 shows a cylinder containing oxygen used in a hospital. Fig. 6.1 (i) Describe how the oxygen molecules exert a pressure on the wall of the cylinder. … … … [2] (ii) The cylinder releases 350 dm3 of oxygen into the atmosphere at a pressure of 101 000 Pa. The volume inside the cylinder is 3.0 dm3. Calculate the pressure of the oxygen in the cylinder before the gas is released. The temperature of the oxygen does not change. State the formula you use and show your working. formula working pressure = … Pa [2] (d) Doctors use radium-223 to treat body cancers. Small quantities of radium-223 are put inside the body. Radium-223 has a half-life of 11.43 days and emits α-radiation. (i) Suggest why an α-source is used to treat cancer cells. … … [1] (ii) Suggest why radium-223 is a suitable α-source for this purpose. … … [1] 223 (iii) 88 Ra decays by α-emission to produce an isotope of radon. Use the correct nuclide notation to complete a symbol equation for this decay process. … … 223 [2] 88Ra … Rn + … He

13 marks

Mark scheme: 6(a)(i) reference to an effect of ionising radiation on body ; 1 6(a)(ii) lead absorbs X-rays / stops X-rays passing through ; 1 6(b)(i) number of oscillations per second ; 1 6(b)(ii) frequency = speed / wavelength or 3 × 108/ 5 × 10–9 ; 6 × 1016 (Hz) ; 2 6(c)(i) collide with walls / cylinder ; (collisions exert a) force on the walls / cylinder ; 2 6(c)(ii) P1 = P2 V2 / V1 or 101 000 × 350 / 3.0 ; = 12 000 000 (Pa) ; 2 6(d)(i) (alpha radiation is) ionising OR kills cells OR low penetration ; 1 6(d)(ii) half life is short / will not radiate for long (in the body) ; 1 6(d)(iii) 223 88Ra → 219 86Rn + 4 2He radon correct ; helium correct ; 2

This question in 0654/43 Oct/Nov 2018

12 Fig. 12.1 shows a solar-powered golf cart, with solar cells on the roof. Fig. 12.1 The solar cells produce electrical energy using solar energy. The Sun is the source of this energy. (a) Name two energy resources that do not have the Sun as their source of energy. 1 … 2 … [1] (b) During the golf cart’s journey, the temperature in the tyres increases. The volume of air in the tyres does not change. Explain in terms of molecules the effect on the pressure of a gas due to an increase in temperature at constant volume. … … … … [2] (c) The golf cart often travels across sloping fields so stability is important in its design. Fig. 12.2 shows the cart on a slope. X Fig. 12.2 The centre of mass of the golf cart is shown by the letter X. State the effect of raising the centre of mass of the golf cart on its stability. … … [1] (d) A spectator takes a photograph of a golfer with a camera. The camera uses a thin converging lens to focus light rays onto the light sensor inside the camera. (i) Complete the ray diagram in Fig. 12.3 to show this. camera lens light rays light from golfer sensor Fig. 12.3 [1] (ii) The lens is made from glass. Glass has a refractive index of 1.33. Define refractive index in terms of the speed of light in a vacuum and in glass. … … [1] (iii) The image produced by the lens on the light sensor is a real image. Describe the difference between a real image and a virtual image. … … [1] (e) Describe in terms of the forces between the atoms why solids have a fixed shape. … … [1] [Total: 8]

8 marks

Mark scheme: 12(a) any two from geothermal nuclear tidal ; 1 12(b) increase in pressure because molecules are moving faster / have more KE ; collide with walls of tyre more frequently / at greater speed / with greater force ; 2 12(c) less stable ; 1 12(d)(i) two straight rays brought to a focus on the light sensor ; 1 12(d)(ii) speed of light in vacuum ÷ speed of light in glass ; 1 12(d)(iii) real image can be projected onto a screen / is formed where the light rays converge ; virtual image is one from which the light rays appear to come from that image ; max 1 12(e) (fixed shape because) strong forces (keep particles in regular / fixed arrangement) ; 1

This question in 0654/41 May/June 2019

6 (a) Fig. 6.1 shows a car with two rear lamps, L1 and L2. L1 L2 Fig. 6.1 The lamps are connected in parallel and powered by a 12 V battery. The lamps each have a resistance of 33 Ω. (i) Calculate the combined resistance of the two lamps connected in parallel in this circuit. Show your working. resistance = … Ω [2] (ii) Calculate the charge that passes through lamp L2 in 30 minutes. State any formula you use and show your working. charge = … C [4] (b) The air in a car tyre exerts a pressure on the walls of the tyre. (i) Use ideas about the motion of molecules to describe how the molecules exert a pressure on the walls of the tyre. … … … [2] (ii) State what happens to the pressure of the air in the tyre if the temperature increases. … … [1] (c) Hot exhaust gases from the car engine leave the engine through a steel exhaust pipe. The steel exhaust pipe transfers thermal energy through the pipe wall by conduction. (i) Describe the process of conduction in a solid, using ideas about particle vibration and transfer by electrons. … … … … … … [3] (ii) When heated, the steel exhaust pipe expands. Explain, in terms of the motion and arrangement of particles, why a solid expands less than a gas when heated. … … … … … [2] [Total: 14]

14 marks

Mark scheme: 6(a)(i) RT = 16.5 (Ω) ; 2 6(a)(ii) current = voltage / resistance or 12 / 33 ; = 0.36 (A) ; charge = current × time or 0.36 × 30 (× 60) ; = 650 (C) ; 4 6(b)(i) (molecules) collide with / hit / rebound from, walls of tyre ; exerting a force ; 2 6(b)(ii) increases ; 1 6(c)(i) incident energy makes particles, vibrate more / gain energy ; this, vibration / energy, is transferred from particle to particle ; reference to, delocalised / free, electrons ; (delocalised / free) electrons transfer energy through the solid ; max 3 6(c)(ii) stronger forces of attraction between particles in solid ; particles in solid are in fixed positions or particles in gas are free to move throughout the gas ; 2

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9 Fig. 9.1 shows a potato being baked in the oven of an electric cooker. Fig. 9.1 (a) The potato has a steel skewer (a long metal pin) pushed through it. When heated the metal skewer expands. Explain in terms of the motion and arrangement of molecules why a solid expands less than a gas when heated. … … … … [2] (b) A thermocouple is used to measure the temperature inside the oven. Describe the structure of a thermocouple. … … [1] (c) The cooker has one electrically heated hotplate. The hotplate uses a current of 2.0 A when used with a mains voltage of 230 V. (i) Calculate the resistance of the hotplate. Show your working. resistance = … Ω [2] (ii) Calculate the energy supplied to the hotplate in 1200 seconds. Show your working. energy = … J [2] (iii) Some water is heated in a saucepan and turns to steam. Describe the differences between water and steam in terms of the forces and distances between the molecules and the motion of the molecules. … … … … [3] [Total: 10]

10 marks

Mark scheme: 9(a) particles in a gas are not/weakly bonded ; particles in a gas move further apart ; 2 9(b) two different metals joined together ; 1 9(c)(i) (R =) V / I or 230 / 2.0 ; = 120 / 115 (Ω) ; 2 9(c)(ii) (E =) V × I × t or 230 × 2.0 × 1200 ; 550 000 / 552 000 (J) ; 2 9(c)(iii) stronger forces of attraction between molecules in liquid water ; molecules are closer together in liquid water ; molecules in liquid water move around each other or molecules in steam move throughout the gas / move further between collisions ; 3

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3 (a) Fig. 3.1 shows a potato being baked in the oven of an electric cooker. potato metal skewer heating element Fig. 3.1 The potato has a metal skewer (a long metal pin) pushed through it. (i) The air in the oven is heated by the heating element. On Fig. 3.1 draw an arrow to show how the heated air moves inside the oven. [1] (ii) Name the main method of thermal energy transfer in the heated air. … [1] (iii) The metal skewer transfers heat to the inside of the potato by conduction. Describe the process of conduction in a solid, using ideas about particle vibration. … … … … [2] (b) The cooker has four electric hotplates, A, B, C and D. These are each connected in parallel with each other across the mains voltage supply. Each hotplate is operated by a separate switch. Each hotplate has a resistance of 60 Ω. Fig. 3.2 shows the circuit. The hotplates are represented by resistor symbols. A B C D Fig. 3.2 (i) Show that the combined resistance of hotplates A and B connected in parallel is 30 Ω. [2] (ii) State the combined resistance of hotplates C and D connected in parallel. … Ω [1] (c) A saucepan containing water is placed on a hotplate. When the temperature of the water reaches the boiling point of water, the water boils. (i) State the boiling point of water. … °C [1] (ii) When the water boils, the liquid water turns into steam. Describe the differences between liquid water and steam in terms of: • the forces and distances between the molecules • the motion of the molecules. … … … … … [3] [Total: 11]

11 marks

Mark scheme: 3(a)(i) arrow showing heated air rising ; 1 3(a)(ii) convection ; 1 3(a)(iii) particles vibrate more / gain energy ; this vibration is passed through metal ; 2 3(b)(i) use of correct formula ; evidence of correct working ; 2 3(b)(ii) 30 Ω ; 1 3(c)(i) 100 (°C) ; 1 3(c)(ii) stronger forces of attraction between water molecules in liquid ; water molecules are closer together in liquid ; water molecules have greater freedom of movement / collide less frequently in steam / owtte ; 3

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6 (a) Dolphins are a species of aquatic mammal. Dolphins produce sound waves in the frequency range 200 Hz–130 000 Hz. State the audible frequency range for a human. from … Hz to … Hz [1] (b) (i) Dolphins locate fish using very high frequency sound called ultrasound. They detect ultrasound reflected from the fish. A dolphin emits a pulse of ultrasound with a frequency of 50 000 Hz. The ultrasound pulse reflects off a fish 20 m away, and returns to the dolphin. The speed of ultrasound in water is 1500 m / s. Calculate the time taken for the ultrasound pulse to reflect off the fish and return to the dolphin. time = … s [2] (ii) Calculate the wavelength of ultrasound waves with a frequency of 50 000 Hz. wavelength = … m [2] (iii) The dolphin changes the frequency of the sound it emits to 100 000 Hz. Suggest what effect, if any, this will have on the time taken for the pulse to travel to the fish and return to the dolphin. Explain your answer. … … … [1] (c) Ultrasound waves travel at 1500 m / s through water. Suggest the speed of these waves through air. Explain your answer. speed … explanation … … [1] (d) Ultrasound waves are longitudinal waves. Electromagnetic waves are transverse waves. Describe the differences between longitudinal and transverse waves. Your description should refer to the direction of propagation of the waves and the direction of oscillation or vibration. You may draw a diagram if it helps your answer. … … … [2] (e) At room temperature, water is a liquid. When water is cooled sufficiently, it turns to ice, a solid. Describe the differences between water and ice, in terms of the forces between molecules and the motion of molecules. … … … … [2] [Total: 11]

11 marks

Mark scheme: 6(a) 20 (Hz) to 20 000 (Hz) ; 1 6(b)(i) (time =) distance / speed or 40 / 1500 ; = 0.027 (s) ; 2 6(b)(ii) (wavelength =) velocity / frequency or 1500 / 50 000 ; = 0.03 (m) ; 2 6(b)(iii) time remains the same because wave velocity doesn’t change ; 1 6(c) any speed lower than 1500 m / s (no mark) ultrasound waves travel slower in a gas compared to a liquid ; 1 6(d) transverse waves – direction of propagation perpendicular to direction of oscillation / vibration ; longitudinal – direction of propagation parallel to direction of oscillation / vibration ; 2 6(e) stronger forces of attraction between water molecules in ice ; water molecules are able to move / ice molecules can only vibrate ; 2

This question in 0654/42 Oct/Nov 2019

6 (a) In a cartoon, a mouse is being chased by a cat. The mouse accelerates constantly from rest for 1 second and reaches a speed of 3 m / s and then moves at a constant speed of 3 m / s for 8 seconds. (i) On the grid in Fig. 6.1 draw the speed-time graph to show the motion of the mouse. 4 3 speed m / s 2 1 0 0 1 2 3 4 5 6 7 8 9 time / s Fig. 6.1 [2] (ii) The cat accelerates constantly from rest for 9 seconds and reaches a speed of 2 m / s. Calculate the acceleration of the cat. acceleration = … m / s2 [2] (b) Fig. 6.2 shows the mouse sitting on a cube of cheese, which is on a wooden beam pivoted in the middle. cheese d cm 20 cm (not to scale) Fig. 6.2 The cat sits on the other end of the beam and balances it. The weight of the cat is 50 N and the combined weight of the mouse and cheese is 21 N. Calculate the distance d when the beam is balanced. distance d = … cm [2] (c) Each side of the cube of cheese is 12 cm. The weight of the cube of cheese is 20.5 N. Calculate the density of the cube of cheese in g / cm3. gravitational field strength = 10 N / kg density = … g / cm3 [4] (d) Water evaporates from the cat’s bowl. Liquid water turns into water vapour when it evaporates. Water also turns into water vapour when water boils. State two differences between the processes of evaporation and boiling. 1 … … 2 … … [2] [Total: 12]

12 marks

Mark scheme: 6(a)(i) acceleration section ; constant speed section ; 2 6(a)(ii) acceleration = change in speed / time OR 2 / 9 ; = 0.2 (m / s2) ; 2 6(b) f1d1 = f2d2 OR 50 × d = 21 × 20 ; d = 8.4 (cm) ; 2 6(c) volume = 1728 (cm3) / use of 123 ; mass = 20.5 / 10 OR 2.05 kg ; 2.05 × 1000 OR 2050 g ; (density = ) 1.2 (g / cm3) ; 4 6(d) evaporation can occur at any temperature / boiling only happens at the boiling point ; evaporation happens at the surface / boiling occurs throughout the liquid ; during boiling all / most molecules have enough energy to leave / evaporation lets only the molecules with most kinetic energy out ; evaporation can occur using the internal energy of the system / boiling a(n external) source of heat ; evaporation produces cooling / boiling does not produce cooling ; evaporation is a slow process / boiling is a rapid process ; max 2 2

This question in 0654/43 Oct/Nov 2019

6 (a) Describe how thermal energy passes through copper by conduction. … … … … [2] (b) Copper boils at 2562 °C. Describe two differences between boiling and evaporation. 1 … … 2 … … [2] (c) Equal volumes of air, copper and water are heated from 10 °C to 90 °C. State which of these materials will expand: most … least. … [1] (d) A copper wire of length 0.5 m has a resistance of 0.02 Ω. Determine the resistance of another copper wire of length 0.25 m that has twice the cross- sectional area. resistance = … Ω [2] (e) Two wires are connected in parallel. One wire has a resistance of 0.40 Ω. The other wire has a resistance of 0.60 Ω. Calculate the combined resistance of the two wires connected together in parallel. resistance = … Ω [2] (f) Copper wire is used in the coil of a generator. Fig. 6.1 shows a simple a.c. generator. Fig. 6.1 (i) On Fig. 6.1 label the coil with the letter C. [1] (ii) An electromotive force (e.m.f.) is induced in the rotating coil. State two factors that would increase the magnitude of the induced e.m.f. 1 … 2 … [2] [Total: 12]

12 marks

Mark scheme: 6(a) thermal energy transferred as (vibrational) energy of atoms ; vibrations passed from atom to atom ; delocalised electrons transfer energy ; max 2 Question Answer Marks 6(b) evaporation can occur at any temperature / boiling occurs at the boiling point; evaporation happens only at the surface / boiling occurs throughout the liquid; during boiling all / most moleculaes have enough energy to leave / evaporation only lets the molecules with the greatest kinetic energy escape; evaporation can occur using the internal energy of the system / boiling requires a(n external) source of heat; evaporation is a slow process / boiling is a rapid process; evaporation produces cooling / boiling does not produce cooling; max 2 6(c) most – air and least copper ; 1 6(d) evidence of division by 2 twice; 0.005 (Ω) ; 2 6(e) 1/RT = 1/R1 + 1/R2 or RT = R1 R2 /R1 + R2 or correct substitution; 0.24 (Ω) ; 2 6(f)(i) coil labelled correctly; 1 6(f)(ii) rotate coil faster ; increase magnetic field strength ; 2

This question in 0654/41 May/June 2020

12 (a) Fig. 12.1 shows an aircraft being refuelled using a plastic pipe. tanker aircraft plastic pipe Fig. 12.1 As the fuel flows through the pipe, the fuel and pipe become electrically charged. Explain why the fuel becomes negatively charged and the pipe becomes positively charged. … … … [2] (b) Fig. 12.2 is the speed-time graph for the aircraft during take-off. 60.0 50.0 40.0 speed 30.0 m / s 20.0 10.0 0.0 10.0 20.0 30.0 40.0 50.0 time / s Fig. 12.2 (i) Calculate the acceleration at 25 seconds. acceleration = … m / s2 [2] (ii) State how the graph shows that the acceleration of the aircraft is constant between 5.0 s and 45.0 s. … … [1] (c) (i) During the flight the pressure inside the aircraft cabin decreases but the temperature is kept constant. Use ideas about gas molecules to describe the change in pressure in terms of the arrangement and motion of molecules. … … … … [2] (ii) The aircraft flies at a high altitude. Some water on the outside of the aircraft body turns to ice. Describe in terms of molecular motion and arrangement how ice differs from liquid water. … … … [2] [Total: 9]

9 marks

Mark scheme: 12(a) transfer of electrons; from pipe to fuel; 2 12(b)(i) correct working (e.g. 50/40) ; 1.25 (m/s2) ; 2 12(b)(ii) straight line; 1 Question Answer Marks 12(c)(i) molecules further apart ; fewer molecules collide with, surfaces / walls, in unit time / lower frequency of collision of molecules with, surfaces / walls ; 2 12(c)(ii) molecular motion – molecules in liquid water can move throughout but molecules in ice vibrate about a fixed point ; molecular arrangement – molecules in liquid water in random arrangement / molecules in ice in regular arrangement ; 2

This question in 0654/41 May/June 2020

9 A mountaineer climbs a mountain. (a) At the top of the mountain there is some ice that is melting in the sunshine. (i) State the melting point of water. … °C [1] (ii) Describe, in terms of molecular motion and arrangement, how liquid water is different from ice. motion … … arrangement … … [2] (b) On the mountain, the mountaineer is exposed to ultraviolet radiation. Ultraviolet radiation is an electromagnetic wave. On Fig. 9.1 write ultraviolet in the correct place in the incomplete electromagnetic spectrum. X-rays visible light radio waves [1] Fig. 9.1 (c) The mountaineer observes lightning striking a nearby mountain. (i) There is an electric field between the negative charge on a cloud and the positive charge on the mountain. State what is meant by an electric field. … … [1] (ii) The lightning occurs when the cloud loses some of its charge to the mountain. The lightning flash discharges 3.0 C in 0.00012 s. Calculate the current that passes. current = … A [2] [Total: 7]

7 marks

Mark scheme: 9(a)(i) 0(°C); 1 9(a)(ii) molecular motion – molecules in liquid water can move throughout but molecules in ice vibrate about a fixed point ; molecular arrangement – molecules in liquid water in random arrangement / molecules in ice in regular arrangement ; 2 9(b) ultraviolet placed between X-rays and visible light; 1 9(c)(i) a region in which an electric charge experiences a force; 1 9(c)(ii) I = Q/t or correct substitution; 25 000 (A); 2

This question in 0654/42 May/June 2020

3 (a) A car travels along a road at 8 m / s. Describe the difference between the terms speed and velocity. … … … [1] (b) Some puddles of water have formed on the road. Explain, in terms of water molecules, how the rate of evaporation of water from a puddle is affected by the strength of the wind blowing across the puddle. … … … … [2] (c) The car battery has an electromotive force (e.m.f.) of 12 V. State what is meant by electromotive force. … … … [2] (d) Fig. 3.1 shows part of the lighting circuit for the car. Two lamps, L1 and L2, each have a resistance of 16 Ω. 12 V fuse L1 L2 Fig. 3.1 (i) When the switch is closed the current in the fuse is 1.5 A. Determine the current in L1. current = … A [1] (ii) State one reason why the lamps are connected as shown in Fig. 3.1 and not in series. Explain your answer. … … … [2] (e) Modern cars use optical fibres to transfer information using visible light rays. Fig. 3.2 shows a ray of light entering an optical fibre. ray of light optical fibre Fig. 3.2 (i) Explain why the ray of light is able to stay inside the optical fibre. You may draw on Fig. 3.2 if it helps your answer. … … … … [2] (ii) Visible light rays are transverse waves. Draw labelled diagrams to show the difference between a transverse wave and a longitudinal wave. [2] [Total: 12]

12 marks

Mark scheme: 3(a) speed has magnitude only / velocity has magnitude and direction / velocity has direction / speed does not have direction ; 1 3(b) increase in wind strength increases rate of evaporation / ORA ; (stronger wind) allows more molecules to escape / evaporate into the air above the puddle / ORA ; 2 3(c) the energy / work done (supplied by a source) ; per (unit) charge ; 2 3(d)(i) 0.75 (A) ; 1 Question Answer Marks 3(d)(ii) if one lamp fails the other will still work ; if one lamp fails still a complete circuit ; OR ref. to full brightness / brighter lamps ; because they each receive the full voltage ; 2 3(e)(i) ref. to total internal reflection / owtte / shown on diagram ; angle of incidence greater than the critical angle ; 2 3(e)(ii) correct diagrams for transverse and longitudinal waves ; vibrations perpendicular to direction of travel for transverse and parallel for longitudinal ; 2

This question in 0654/41 Oct/Nov 2020

3 (a) A golfer swings her golf club to hit a stationary golf ball of mass 0.05 kg. (i) State the kinetic energy of the golf ball before it is hit. kinetic energy = … J [1] (ii) The speed of the golf ball immediately after it has been hit is 35 m / s. Calculate the kinetic energy of the golf ball when it is moving at 35 m / s. kinetic energy = … J [2] (b) When the golfer hits the ball, she hears a sound. Sound waves are longitudinal waves and pass through the air as a series of compressions and rarefactions. (i) State what is meant by a longitudinal wave. … … [1] (ii) Describe one difference between a compression and a rarefaction. … … [1] (iii) Fig. 3.1 shows a sound wave travelling through the air. Fig. 3.1 On Fig. 3.1, label a compression with the letter C and a rarefaction with the letter R. [2] (c) Part of a golf club is made of solid metal. Explain why solids have a fixed shape. Use ideas about the forces between atoms in your answer. … … [1] [Total: 8]

8 marks

Mark scheme: 3(a)(i) 0 (J) ; 1 3(a)(ii) KE = 1 / 2mv2 or working ; 31 (J) ; 2 3(b)(i) longitudinal wave oscillates / vibrates parallel to direction of movement of wave / energy transfer ; 1 3(b)(ii) compression is region of, high pressure or molecules / particles, closer together / ORA ; 1 Question Answer Marks 3(b)(iii) compression correctly labelled ; rarefaction correctly labelled ; 2 3(c) strong forces of attraction between atoms hold atoms together in a fixed position ; 1

This question in 0654/42 Oct/Nov 2020

6 (a) A boat has a mass of 2000 kg. (i) State the kinetic energy of the boat when the boat is not moving. kinetic energy = … J [1] (ii) Calculate the kinetic energy of the boat when it moves at a constant speed of 11 m / s. kinetic energy = … J [2] (b) The boat reaches the entrance to a harbour. Fig. 6.1 shows five wavefronts approaching the narrow harbour entrance. sea wavefront direction of travel of waves harbour wall harbour land entrance Fig. 6.1 On Fig. 6.1, draw two wavefronts after they pass through the harbour entrance. [2] (c) There is water on the deck of the boat. The water slowly evaporates. State two conditions that could change so that the water evaporates faster. 1 … 2 … [2] (d) A seabird of mass 1.2 kg lands on the deck of the boat. The total area of the seabird’s two feet in contact with the deck is 5.4 cm2. Calculate the pressure exerted by the seabird on the deck when it is standing on two feet. The gravitational field strength g is 10 N / kg. pressure = … N / cm2 [3] [Total: 10]

10 marks

Mark scheme: 6(a)(i) 0 (J); 1 6(a)(ii) (ke =) ½mv2 or ½ × 2000 × 112 or ½ × 2000 × 121; (ke =) 121 000 (J); 2 6(b) wavefronts curve as shown ; wavelength unchanged ; 2 Question Answer Marks 6(c) (increase) temperature ; (more) air flow ; (increase) surface area of puddle ; humidity ; AVP ; max 2 2 6(d) (W =) mg / 1.2 × 10 / 12 ; (p =) F / A / 12 / 5.4 ; pressure = 2.2 (N / cm2); 3

This question in 0654/43 Oct/Nov 2020

6 (a) Electricity may be obtained using the sources listed. fossil fuels geothermal solar tidal wind (i) State which of the sources of energy is non-renewable. … [1] (ii) State which two of the sources of energy are not dependent on the Sun. … and … .[1] (b) Many types of power station use steam to turn a turbine attached to a generator. Explain, in terms of the forces and distances between molecules and the motion of molecules, why steam is able to fill its container. … … … … … … [3] (c) Fig. 6.1 shows a diagram of a simple a.c. generator. coil N S a.c. output Fig. 6.1 (i) Explain why the generator produces an a.c. output. … … … … … … [3] (ii) On the grid provided in Fig. 6.2, sketch a graph of voltage output against time for this generator. You must show at least one full cycle. voltage output 0 time Fig. 6.2 [1] [Total: 9]

9 marks

Mark scheme: 6(a)(i) fossil fuels ; 1 6(a)(ii) geothermal and tidal ; 1 6(b) any three from: particles are free to move / particle movement is random ; rapid movement of particles / high kinetic energy of particles ; particles are far apart / low particle density ; forces between molecules are, weak / zero ; 3 Question Answer Marks 6(c)(i) any two from: the coil turns ; in a magnetic field / cuts a magnetic field / experiences a changing magnetic flux ; induces emf ; plus: changes direction every half turn ; 3 6(c)(ii) sine wave ; 1

This question in 0654/42 Feb/March 2021

9 Fig. 9.1 shows the motion of a sprinter running a race. 9.0 8.0 velocity m / s 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 time / s Fig. 9.1 (a) Describe the motion of the sprinter during the first 0.5 seconds of the race. … … [1] (b) Show that the maximum acceleration of the sprinter is 2.0 m / s2. [1] (c) This acceleration is caused by a resultant force of 160 N. Calculate the mass of the sprinter. mass = … kg [2] (d) Fig. 9.2 shows the forces acting on the sprinter at various points during the race. The lengths of the arrows represent the magnitude of the forces. (i) Put a tick (3) in the box which shows the horizontal forces acting on the sprinter 5.0 s after the race started. Fig. 9.2 [1] (ii) Use the motion of the sprinter in Fig. 9.1 to explain your answer to (d)(i). … … … [1] (e) At the end of the race, the sprinter’s skin is coated in a layer of sweat. (i) Describe, in terms of particles and their energies, how the sweat cools the skin. … … … … … [3] (ii) Describe two differences between evaporation and boiling. 1 … … 2 … … [2] [Total: 11]

11 marks

Mark scheme: 9(a) stationary ; 1 9(b) (a =) 8.0 / 4.0 ; 1 9(c) (m =) F / a or 160 / 2.0 ; 80 (kg) ; 2 9(d)(i) first diagram ticked ; 1 9(d)(ii) constant velocity / no acceleration, so forces must be balanced / no resultant force ; 1 Question Answer Marks 9(e)(i) (water) evaporates ; most energetic particles leave (surface) ; average energy of the remaining particles is lower ; 3 9(e)(ii) evaporation can occur at any temperature / boiling only happens at the boiling point ; evaporation happens only at the surface / boiling happens throughout the liquid ; boiling takes energy in (endothermic) to occur / evaporation lets only the molecules with the highest kinetic energy out ; evaporation can occur using the internal energy of the system / boiling requires an external source of heat ; evaporation produces cooling / boiling does not ; evaporation is a slow process / boiling is a rapid process ; max 2 2 4

This question in 0654/41 May/June 2021

6 (a) Metals are good conductors of thermal energy. Describe the two mechanisms of energy transfer that make metals good thermal conductors. 1 … … 2 … … [2] (b) A student investigates how the surface colour of an object affects how fast the object loses thermal energy. Fig. 6.1 shows the equipment used. thermometer thermometer Fig. 6.1 She uses two identical aluminium cans one of which has been painted black and the other white. She fills both cans with an equal volume of hot water at the same temperature and records the temperature of the water every minute for 60 minutes. Fig. 6.2 shows her results. 100 temperature 80 / °C 60 Q 40 P 20 0 0 10 20 30 40 50 60 time / min Fig. 6.2 (i) Use the information in Fig. 6.2 to state the temperature of the room. … °C [1] (ii) State which line in Fig. 6.2, P or Q, is for the can painted black. Explain your answer in terms of energy transfer by radiation. line … explanation … … … … [2] (c) The student reheats the water in one of the cans using an electric immersion heater. The heater has a power rating of 1.5 kW and is switched on for 120 seconds. (i) Calculate the amount of energy used by the electric immersion heater. energy = … J [3] (ii) State the amount of electrical work done by the heater during this process. … [1] (d) During the experiment, the student spills some water on the table. The water evaporates. State two ways to increase the rate of evaporation. 1 … … 2 … … [2] [Total: 11]

11 marks

Mark scheme: 6(a) vibration of particles / atoms / ions ; transfer by electrons ; 2 6(b)(i) 20(°C) ; 1 6(b)(ii) P, takes less time to cool to room temp / cools quicker ; black emits, radiation / heat energy / energy, more quickly than white ; 2 6(c)(i) 1500 / 1.5 × 103 ; (E =) Pxt / 1500 × 120 ; 180 000 (J) ; 3 6(c)(ii) 180 000 (J) ; 1 6(d) any two from: increase temperature ; increase surface area ; draught over surface ; AVP ; 2

This question in 0654/42 May/June 2021

12 Fig. 12.1 shows the arrangement of molecules in samples of a solid, a liquid and a gas. solid liquid gas Fig. 12.1 (a) Some statements about the structure and properties of matter are given. Place a tick (3) next to all of the statements that describe the structure or properties of a solid. There are no forces between molecules. Forces between molecules are strong. It has a fixed volume. It can be compressed. Molecules can only vibrate. Molecules are free to move. [3] (b) Fig. 12.2 shows a syringe filled with a gas similar to the sample shown in Fig. 12.1. The syringe is attached to a pressure gauge which measures the pressure of the gas. syringe 5 10 15 20 pressure gauge cm3 Fig. 12.2 Describe what causes the pressure in the sample of gas in terms of molecular motion. … … … … [2] (c) A student conducts an investigation into how the pressure of the gas changes with volume. The temperature of the gas remains constant. Fig. 12.3 shows the results of the student’s investigation. 1000 pressure / kPa 800 600 400 200 00 5 10 15 20 volume / cm3 Fig. 12.3 (i) Use Fig. 12.3 to determine the volume of the sample of gas when the pressure is 500 kPa. volume = … cm3 [1] (ii) The mass of the sample of gas is 2.45 g. Calculate the density of the sample of gas when the pressure is 500 kPa. density = … g / cm3 [2] (d) Explain why increasing the temperature of a sample of gas, while keeping the volume constant, causes an increase in pressure. … … … … [2] [Total: 10]

10 marks

Mark scheme: 12(a) forces between molecules are strong ; it has a fixed volume ; molecules can only vibrate; 3 12(b) collisions of molecules with walls ; produces a force ; 2 12(c)(i) 5 (cm3) ; 1 12(c)(ii) (density =) m / V or 2.45 / 5 ; 0.5 (g / cm3) ; 2 12(d) molecules move faster / have more energy ; molecules collide, more often / more frequently, with walls / with a larger force exerted on walls ; 2

This question in 0654/43 May/June 2021

9 Fig. 9.1 shows a person sitting in an inflatable raft. Fig. 9.1 (a) The raft consists of a large rubber tube inflated with air. (i) Describe how the motion of the air molecules causes pressure inside the rubber tube. … … … … [2] (ii) As the sun warms up the air inside the rubber tube, the pressure increases. Explain why the pressure increases. … … … … … [3] (b) The combined weight of the raft and the person is 1100 N. The raft exerts a pressure of 500 Pa on the surface of the water. (i) Calculate the area of raft in contact with the water. area = … m2 [2] (ii) The tide causes the raft to move at a speed of 4.0 m / s. Calculate the kinetic energy of the raft and the person. gravitational field strength g = 10 N / kg kinetic energy = … J [3] (iii) State what causes tides. … [1] [Total: 11]

11 marks

Mark scheme: 9(a)(i) collisions of molecules with walls / raft ; produces a force ; 2 9(a)(ii) molecules move faster / have more (kinetic) energy ; molecules collide more often / more frequently with walls ; larger force exerted on walls ; 3 9(b)(i) (A =) F÷ P or 1100÷ 500 ; 2.2 (m2) ; 2 9(b)(ii) (mass =) 110 kg ; (KE =) ½ mv2 or ½ × 110 × 42 ; 880 (J) ; 3 9(b)(iii) the moon ; 1

This question in 0654/41 Oct/Nov 2021

9 Fig. 9.1 shows a helium filled balloon attached to a spring. The spring is attached to a table top to stop the balloon moving upwards. The balloon is in equilibrium. Fig. 9.1 (a) The helium filled balloon has a mass of 6.5 g. (i) Calculate the weight of the helium filled balloon. gravitational field strength g = 10 N / kg weight = … N [2] (ii) The balloon causes the spring to extend by 0.50 cm. The spring constant of the spring is 0.45 N / cm. Calculate the force on the spring. force = … N [2] (iii) State the total downwards force acting on the balloon. force = … N [1] (b) A student places the balloon under an infrared lamp to warm the helium gas. (i) Suggest the colour of balloon which will give the greatest rate of increase in gas temperature. Explain your answer. colour … explanation … … [2] (ii) Explain why the size of the balloon increases as it is heated. … … … … … [3] [Total: 10]

10 marks

Mark scheme: 9(a)(i) (W =) mg or 0.0065 × 10 ; 0.065 (N) ; 2 9(a)(ii) (F =) kx or 0.45 × 0.50 ; 0.225 (N) ; 2 9(a)(iii) 0.29 (N) ; 1 9(b)(i) black ; absorbs more, radiation / heat, than other colours ; 2 9(b)(ii) molecules, gain kinetic energy / speed up / move faster ; molecules collide more often with the balloon / so the molecules exert a larger force on the inside of the balloon ; so the molecules exert higher pressure ; 3

This question in 0654/42 Oct/Nov 2021

12 (a) Fig. 12.1 shows a sealed glass jar filled with pure oxygen gas. Each oxygen molecule has a mass of 5.34 × 10–26 kg. Fig. 12.1 (i) Describe how the motion of the oxygen molecules causes pressure inside the glass jar. … … … … [2] (ii) The average kinetic energy of a molecule of oxygen is 2.67 × 10–22 J. Calculate the average speed of a molecule of oxygen. average speed = … m / s [2] (b) Fig. 12.2 shows a sample of gas in a sealed container attached to a pressure gauge. pressure gauge Fig. 12.2 The temperature of the gas is increased and the pressure is measured. Fig. 12.3 shows how the pressure changes with temperature. 400 pressure / kPa 300 200 100 0 0 50 100 150 200 temperature / °C Fig. 12.3 (i) Describe the results shown in Fig. 12.3. … … … … [2] (ii) A student suggests repeating the experiment with a non-flammable balloon filled with gas rather than a sealed container. Explain why this method would not produce the graph shown in Fig. 12.3. … … [1] [Total: 7]

7 marks

Mark scheme: 12(a)(i) collisions between molecules and wall of container / jar ; causes a force ; 2 12(a)(ii) (v =) 2E m or 22 26 2 2.67 10 5.34 10 − − × × × ; 100 (m / s) ; 2 12(b)(i) pressure increases as temperature increases ; at a uniform / linear rate / proportionally; 2 12(b)(ii) volume would not be constant ; 1

This question in 0654/43 Oct/Nov 2021

9 A student investigates the motion of pollen grains in water seen through a microscope. The student observes that the pollen grains constantly move short distances in random directions. (a) Fig. 9.1 shows the pollen grains suspended in water. Fig. 9.1 (i) State the name given to the motion of these pollen grains. … [1] (ii) Explain why the pollen grains constantly move short distances in random directions. … … … … [2] (b) The microscope uses a thin converging lens to produce an image. Fig. 9.2 shows a thin converging lens. object F F F = principal focus Fig. 9.2 (i) Draw a ray diagram on Fig. 9.2 to show the formation of a real image. Label the image with the word image. [3] (ii) The image formed is a real image. Describe one difference between a real image and a virtual image. … … [1] (c) The visible light that passes through the lens is part of the electromagnetic spectrum. (i) State the speed of visible light in a vacuum. … [1] (ii) γ‑rays and radio waves are also part of the electromagnetic spectrum. Place ticks (✓) in the boxes in Table 9.1 to show which statements are true for γ‑rays and radio waves. Table 9.1 γ‑rays radio waves is used in communication is used in medicine can cause cancer is higher frequency than visible light has a longer wavelength than visible light [3] [Total: 11]

11 marks

Mark scheme: 9(a)(i) Brownian (motion) ; 1 9(a)(ii) ref to collisions (of pollen grains) ; with, light fast-moving particles / water particles or molecules ; 2 9(b)(i) ;; image labelled ; 3 9(b)(ii) real image can be projected on to a screen / is formed when rays of light actually meet / ORA ; 1 F = principal focus Question Answer Marks 9(c)(i) 3  108 m / s ; 1 9(c)(ii) ;;; 3

This question in 0654/42 May/June 2022

6 Fig. 6.1 shows a cheetah. Cheetahs are the fastest land animal and have a top speed of 30 m / s. Fig. 6.1 (a) State the difference between speed and velocity. … … [1] (b) Fig. 6.2 shows a speed–time graph for a cheetah’s journey. 30 25 20 speed 15 m / s 10 5 0 0 2 4 6 8 10 time / s Fig. 6.2 Describe the motion of the cheetah shown in Fig. 6.2. … … … … … … [3] (c) The mass of the cheetah is 42 kg. Calculate the kinetic energy of the cheetah when it is running at its maximum speed of 30 m / s. kinetic energy = … J [2] (d) A cheetah drinks water from a puddle. Over time, the water in the puddle evaporates. Evaporation and boiling both turn liquid water into a gas. (i) State one difference between evaporation and boiling. … … [1] (ii) State two ways to increase the rate of evaporation from the puddle. 1 … … 2 … … [2] [Total: 9]

9 marks

Mark scheme: 6(a) velocity has direction / ORA ; 1 6(b) acceleration ; constant followed by non-constant ; constant speed / zero acceleration ; 3 6(c) (KE =) ½ mv2 OR ½  42  302 ; 18 900 (J); 2 6(d)(i) Any one from evaporation can occur at any temperature / boiling only happens at the boiling point ; evaporation happens only at the surface / boiling happens throughout the liquid; during evaporation only the molecules with the highest (kinetic) energy leave / during boiling all molecules have enough energy to leave ; evaporation can occur using the internal energy of the system / boiling requires an external source of heat ; evaporation produces cooling / boiling does not ; evaporation is a slow process / boiling is a rapid process ; 1 6(d)(ii) increase temperature ; increase surface area ; increase draught ; max 2 2

This question in 0654/43 May/June 2022

9 Burning coal can be used to generate electricity. (a) State one advantage and one disadvantage of using coal to generate electricity. advantage … … disadvantage … … [2] (b) The thermal energy released by the coal is used to turn liquid water into steam. (i) Compare the: • forces between molecules • distances between molecules • motions of molecules in a liquid at 100 °C and a gas at 100 °C. forces between molecules … distances between molecules … motions of molecules … … [3] (ii) Complete Table 9.1 to describe what happens to the pressure in a sample of steam under different conditions. Assume the steam remains as a gas under each set of conditions. Use the words increases, decreases or remains constant. You can use each word once, more than once or not at all. Table 9.1 temperature volume pressure increases remains constant decreases remains constant remains constant increases remains constant decreases [2] (c) A transformer is used to change the potential difference of the output from a coal-fired power station. The transformer is made up of a primary coil and a secondary coil, wrapped around an iron core. (i) The potential difference across the primary coil is 20 kV. The primary coil contains 120 turns. The potential difference across the secondary coil is 400 kV. Calculate the number of turns on the secondary coil. number of turns = … [2] (ii) The electric power is transported from the power station over large distances at 400 kV. This is a very high potential difference. Explain why a very high potential difference is used. … … … … … [2] [Total: 11]

11 marks

Mark scheme: 9(a) (advantage) 2 high energy density / fast start up of power stations / abundant / easily available / easy to transport or store / reliable / easily combustible / AVP ; (disadvantage) releases CO2 / causes global warming / climate change / finite or non-renewable resource / releases SO2 / causes acid rain / pollution from particulates / AVP ; 9(b)(i) (forces) stronger in liquid / ORA ; 3 (distance) closer in liquid / ORA ; (motion) molecules are freer to move in gas / ORA ; 9(b)(ii) increases 2 decreases ; decreases increases ; 9(c)(i) use of Vp / Vs = Np / Ns ; 2 2400 ; 9(c)(ii) reduces current ; 2 reduces, power or energy losses / less heat generated ;

This question in 0654/42 Oct/Nov 2022

2 Fig. 2.1 shows a person removing a damaged branch from a tree. Fig. 2.1 (a) The damaged branch has a mass of 225 kg and is lowered 5.2 m to the ground. Calculate the change in gravitational potential energy (GPE) of the branch as it is lowered to the ground. The gravitational field strength, g = 10 N / kg. change in GPE = … J [2] (b) The damage to the tree was caused by a lightning strike during a thunderstorm. (i) A scientist estimates that the lightning strike transferred 6000 C of charge in 0.20 s. Calculate the average current in the lightning strike. current = … A [2] (ii) The thunderstorm produces both light and sound waves. Explain why an observer sees the light before they hear the sound. … … … … [2] (c) Lightning is caused by electrostatic charges in clouds. Fig. 2.2 shows how charge can form an electric field inside the cloud. positive charge + + + + + + + + electric field _ _ _ _ _ _ _ _ negative charge Fig. 2.2 (i) Fig. 2.2 shows negative charge at the base of the cloud. State the name of the particles that provide this negative charge. … [1] (ii) Describe what is meant by an electric field. … … [1] (d) Thunderstorms can produce gamma radiation and X‑rays as well as visible light. Use the phrases to complete the sentences. You may use each phrase once, more than once or not at all. less than more than the same as The speed of visible light is … the speed of X‑rays. The wavelength of gamma radiation is … the wavelength of visible light. The frequency of X‑rays is … the frequency of gamma radiation. [2] (e) When lightning passes through the air, it heats the air up to 10 000 °C. State and explain what happens to the volume of the air when the temperature increases. Use ideas about molecules in your answer. … … … … [2] [Total: 12]

12 marks

Mark scheme: 2(a) evidence of (GPE =) mgh (in any form) or 225  10  5.2 ; 2 (GPE =) 11 700 (J) ; 2(b)(i) evidence of (I =) Q / t (in any form) or 6000 / 0.20 ; 2 (I =) 30 000 (A) ; 2(b)(ii) light travels faster than sound ; 2 both waves travel the same distance / over a large distance the difference in time is noticeable ; 2(c)(i) electrons ; 1 2(c)(ii) a region in which charged particles experience a force ; 1 2(d) the same as ; 2 less than AND less than ; 2(e) (volume) increases / expands ; 2 molecules, have more (kinetic) energy / move faster or molecules move further apart ;

This question in 0654/42 Feb/March 2023

3 An Olympic triathlon event consists of a 1500 m swim, a 40 km cycle ride and a 10 km run. (a) Fig. 3.1 shows an athlete swimming at a constant speed. A B Fig. 3.1 (i) Describe how the size of force A compares with the size of force B. … … [1] (ii) The athlete has a weight of 750 N and moves with a kinetic energy of 13.5 J. Calculate the speed of the athlete. The gravitational field strength, g, is 10 N / kg. speed = … m / s [2] (b) Fig. 3.2 shows a speed–time graph for the start of the cycle ride. 70.0 60.0 50.0 40.0 speed km/h 30.0 20.0 10.0 0.0 0 10 20 30 40 time / s Fig. 3.2 (i) Show that the maximum speed of the athlete during the first 40 seconds of the cycle ride is 12.5 m / s. [1] (ii) Calculate the acceleration of the athlete during the first 25 seconds of the cycle ride. Give your answer in m / s2. acceleration = … m / s2 [2] (iii) Calculate the distance covered by the athlete during the first 35 seconds of the cycle ride. distance = … m [2] (iv) Fig. 3.3 shows the pedal of the bicycle as the athlete pedals. F 0.17 m Fig. 3.3 The moment of the force applied by the athlete is 35.7 N m. Use Fig. 3.3 to calculate the force exerted by the athlete on the pedal. force = … N [2] (c) During the run, the athlete starts to sweat. Explain, in terms of the motion and energy of water molecules, how sweating cools the athlete’s skin. … … … … … … [3] [Total: 13]

13 marks

Mark scheme: 3(a)(i) (the forces are) the same size / equal ; 1 3(a)(ii) (mass =) 750 / 10 / 75 (kg) AND (speed = ) √ (2  13.5) / 75 ; (speed = ) 0.6 (m / s) ; 2 3(b)(i) 45000 / 3600 (=12.5 m / s) ; 1 3(b)(ii) (a = ) v / t / 12.5 / 25 ; (a = ) 0.5 (m / s2) ; 2 3(b)(iii) (0.5  25  12.5) + (12.5  10) ; 281.25 (m) ; 2 3(b)(iv) (force = ) moment / distance / 35.7 / 0.17 ; (force = ) 210 (N) ; 2 3(c) (thermal) energy is transferred (from skin / blood / capillaries) to water molecules (on skin surface) ; the most energetic molecules escape / evaporates from the surface ; average energy of remaining molecules decreases ; 3

This question in 0654/41 May/June 2023

12 (a) Table 12.1 shows information about three types of ionising radiation. Table 12.1 type of ionising relative nature of radiation relative penetrating ability radiation ionising effect alpha high … … beta fast‑moving electron medium medium gamma electromagnetic radiation low … (i) Complete Table 12.1. [2] (ii) Fig. 12.1 shows the path taken by a beta particle as it moves through an electric field. Complete Fig. 12.1 to show the paths taken by alpha particles and gamma rays as they pass through an electric field. + − + − + − + − + − alpha beta gamma Fig. 12.1 [2] (b) Beta particles are released when carbon‑14 (146C) decays into an isotope of nitrogen. Use the correct nuclide notation to complete the decay equation for carbon‑14. 14 … … 6C … N + … β [2] (c) At room temperature, nitrogen is a gas, water is a liquid and carbon is a solid. (i) Explain why a gas can be compressed and a solid cannot be compressed. … … … [1] (ii) Suggest if water can be compressed. Give a reason for your answer. … … … [1] (iii) A sample of nitrogen gas is held in a container with a fixed volume. The temperature of the nitrogen is increased. Explain the effect that increasing the temperature of the gas has on the pressure in the gas. Use ideas about molecules in your answer. … … … … … … [3] [Total: 11]

11 marks

Mark scheme: 12(a)(i) He nucleus / 2 protons and 2 neutrons and low ; high ; 2 12(a)(ii) alpha curves towards negative ; gamma does not deviate ; 2 12(b)     14 14 0 6 7 1 C N ;; 2 12(c)(i) in a gas the particles are far apart / in a solid the particles are touching ; or in a gas the particles can be pushed closer together / the particles in a solid can’t be pushed closer together ; 1 12(c)(ii) (water cannot be compressed) (because) the molecules are touching or there are no / small, gaps between molecules ; 1 Question Answer Marks 12(c)(iii) (kinetic) energy / speed of molecules, increases ; molecules collide with the (walls of the) container, more often / harder ; the force per unit area increases / the pressure increases ; 3

This question in 0654/42 May/June 2023

6 Fig. 6.1 shows a bee collecting pollen from a flower. Fig. 6.1 (a) The maximum speed of a bee is 5.8 m / s. (i) Calculate the maximum distance a bee can travel in 60 seconds. maximum distance = … m [2] (ii) The mass of the bee is 0.20 g. Calculate the kinetic energy of the bee when it is moving at 5.8 m / s. kinetic energy = … J [3] (b) The flower uses brightly coloured petals to attract the bee. The petals reflect ultraviolet light and visible light, both of which are part of the electromagnetic spectrum. State one similarity and one difference between visible light and ultraviolet light. similarity … … difference … … [2] (c) The bee becomes positively charged as it flies through the air. Suggest how this charge is produced. … … … … … [3] (d) When suspended in water, the pollen from the flower can be used to study Brownian motion. Describe how Brownian motion provides evidence for the kinetic molecular model of matter. … … … … … [3] [Total: 13]

13 marks

Mark scheme: 6(a)(i) (d =) v  t / (d =) 5.8  60 ; 2 348 or 350 (m) ; 6(a)(ii) conversion: (0.20 g =) 0.00020 kg ; 3 (KE =) ½ mv2 / ½  0.00020  5.82 ; (KE =) 0.0034 or 3.4  10–3 (J) ; 6(b) similarity: travel at speed of light / transverse waves ; 2 difference: (visible light has lower) frequency / (visible light has longer) wavelength / ORA ; 6(c) friction (with air) ; 3 (negative) electrons (move) ; (electrons move) off (surface of) bee ; 6(d) random motion (of pollen grains / particles) ; 3 caused by collisions with water / molecules / other particles ; (movement because of idea of) fast(er) moving small(er) particles ;

This question in 0654/41 Oct/Nov 2023

9 A student is investigating electromagnetic induction by dropping a magnet through a coil of wire. The coil of wire is connected to a device which measures the electromotive force (e.m.f.) induced in the coil. Fig. 9.1 shows the equipment used by the student. N direction of motion of magnet S to device to measure e.m.f. coil of wire Fig. 9.1 (a) Fig. 9.2 shows the induced electromotive force (e.m.f.) measured as the magnet falls through the coil of wire. Fig. 9.2 shows two peaks, X and Y. +0.6 peak X +0.4 +0.2 induced e.m.f . / V 0.0 time / s 0.02 0.04 0.06 0.08 –0.2 –0.4 –0.6 peak Y Fig. 9.2 (i) Explain why: peak X is positive and peak Y is negative … … peak Y has a larger magnitude than peak X. … … [2] (ii) The data in Fig. 9.2 was obtained using a coil made of 800 turns of wire. On Fig. 9.2, sketch the data which would be obtained if a coil containing 400 turns was used with the same magnet. [2] (b) When writing up the results, the student is not sure whether to write about the induced potential difference or the induced electromotive force (e.m.f.). Place ticks in Table 9.1 against each statement that is correct for potential difference and for electromotive force (e.m.f.). You may place one or two ticks in each row. The first row has been done for you. Table 9.1 electromotive potential force (e.m.f.) difference is measured in volts 3 3 is equal to work done per unit charge relates to the energy supplied by the source relates to the energy transferred by a circuit component [2] (c) The coil of wire used in the investigation is made of copper. Copper is a solid. Complete the sentences to describe the arrangement of atoms in a solid and the properties of a solid. In a solid, the arrangement of atoms is … . The forces between atoms are … which allows the atoms to … but keeps them in a … position. [2] (d) Copper is a good thermal conductor. Describe how thermal energy is transferred in copper. … … … … [3] [Total: 11]

11 marks

Mark scheme: 9(a)(i) (peak X is positive and peak Y is negative) 2 S causes peak (X) and N causes peak (Y) (as it passes through coil) ; (peak Y has a larger magnitude than X) (idea that) the magnet is increasing in velocity / speed ; 9(a)(ii) 2 same shape graph drawn with line crossing x-axis at same point ; both peaks lower than original ; 9(b) 2 electromotive potential force (e.m.f.) difference is measured in volts ✓ ✓ is equal to work done per unit charge ✓ ✓ relates to the energy supplied by the source ✓ relates to the energy transferred by a circuit component ✓ ;; 9(c) regular / ordered / a lattice 2 strong vibrate fixed ;; four correct = 2 marks two or three correct = 1 mark 9(d) atoms vibrate ; 3 (idea that) vibrations passed on to next atom ; (idea of) transfer by (free) electrons ;

This question in 0654/41 Oct/Nov 2023

6 Fig. 6.1 shows an electric pressure‑washer being used to wash a car. to power supply Fig. 6.1 (a) The pressure‑washer pumps water at a high pressure through a small nozzle. The cross‑sectional area of the nozzle is 5.0 × 10–6 m2. The water leaves the nozzle with a pressure of 9.0 × 106 Pa. Calculate the force exerted by the water as it leaves the nozzle. force = … N [2] (b) The pressure‑washer uses a d.c. motor to pump the water out of the nozzle. Fig. 6.2 shows a diagram of a simple d.c. motor. N X S _ + Fig. 6.2 (i) The arrows on Fig. 6.2 show the direction of the current. Draw an arrow to show the direction of the force acting on the coil at the point labelled X. [1] (ii) Describe the function of the split‑ring commutator in a simple d.c. motor. … … … … [2] (c) After the car has been washed, droplets of cold water remain on the roof of the car. After a few minutes, the droplets of water have disappeared. (i) State the name of the process which causes the droplets of water to disappear. … [1] (ii) Describe the process which causes the droplets of water to disappear in terms of molecules. … … … [2] [Total: 8]

8 marks

Mark scheme: 6(a) (F=) 45 (N) ; 2 6(b)(i) arrow drawn upwards ; 1 6(b)(ii) provides an alternating current (in the coil) / current that changes direction every half-turn / to reverse the current every half turn / 180° ; allows coil to continue to turn (in the same direction) ; 2 Question Answer Marks 6(c)(i) evaporation ; 1 6(c)(ii) the most energetic molecules ; escape from the surface ; 2

This question in 0654/42 May/June 2024

9 A student is investigating resistance. (a) Fig. 9.1 shows the circuit made by the student. V I1 I2 2.5 Ω 2.5 Ω 2.5 Ω V1 V2 V3 Fig. 9.1 (i) State how the currents labelled I1 and I2 compare with each other. … [1] (ii) Write an equation showing the relationship between the reading on the voltmeter, V, and the three potential difference values V1, V2 and V3. … [1] (iii) Calculate the total resistance of the circuit. total resistance = … Ω [1] (iv) The reading on the voltmeter in Fig. 9.1 is 1.5 V. Calculate the value of the current I1. State the unit for your answer. current = … unit … [3] (b) The student replaces the three fixed resistors with one thermistor, moves the voltmeter and includes an ammeter. Fig. 9.2 shows the new circuit made by the student. A V Fig. 9.2 (i) The student observes the readings on the ammeter and voltmeter as the thermistor is moved from a warm room into a beaker of ice. State and explain what the student observes on the ammeter and voltmeter. ammeter … … … voltmeter … … … [2] (ii) While the student is conducting the experiment, the ice in the beaker melts into liquid water. Compare the arrangement and motion of molecules in a solid to the arrangement and motion of molecules in a liquid. arrangement … … motion … … [2] [Total: 10]

10 marks

Mark scheme: 9(a)(i) 1 9(a)(ii) V = V1 + V2 + V3 ; 1 9(a)(iii) 7.5 () ; 1 9(a)(iv) (I=) V / R / 1.5 / 7.5 ; (I=) 0.20 ; A / amp / amps / amperes ; 3 9(b)(i) (ammeter:) decreases because the resistance of the thermistor increases ; (voltmeter:) stays the same because it receives the full voltage / owtte ; 2 9(b)(ii) (arrangement:) solid is regular and liquid is random ; (motion:) solid molecules vibrate about a fixed point and liquid molecules can move / slide (past each other) ; 2

This question in 0654/43 May/June 2024

12 Polonium is a highly radioactive metal with no stable isotopes. (a) Polonium-210 (21084Po) decays to form lead-206 (20682Pb). The decay of polonium-210 is a one-step process. (i) State the type of ionising radiation emitted when polonium-210 decays to lead-206. … [1] (ii) The half-life of polonium-210 is 140 days. The activity of a sample of polonium-210 is measured as 680 counts per minute. Calculate the time taken, in days, for the activity to decrease to 85 counts per minute. time = … days [2] (b) Polonium is a solid at room temperature. The melting point of polonium is 254 °C. (i) Explain, in terms of the motion and arrangement of atoms, why a fixed mass of solid polonium will occupy a smaller volume than the same mass of liquid polonium. … … … … … … [3] (ii) The density of solid polonium is 9.4 g / cm3. Calculate the volume occupied by 235 g of solid polonium. volume = … cm3 [2] [Total: 8]

8 marks

Mark scheme: 12(a)(i) alpha (particle) ; 1 12(a)(ii) reference to 3 half-lives ; 2 (140  3 =) 420 (days) ; 12(b)(i) idea that, both samples contain the same number of atoms (as they have the same mass) ; 3 atoms in a solid vibrate (about fixed positions) and atoms in a liquid are free to move ; atoms in a solid are in a regular arrangement and atoms in a liquid are in a random / irregular arrangement (so take up more space) ; 12(b)(ii) evidence of V = m ÷ or 235 ÷ 9.4 ; 2 (V =) 25 (cm3) ;

This question in 0654/42 Oct/Nov 2024

12 Fig. 12.1 shows a diagram of a nuclear power station used to generate electricity. boiler control rod steam fuel rod moderator steam turbine generator to cooling tower reactor pump condenser Fig. 12.1 (a) (i) State the process in the reactor that releases energy. … [1] (ii) Complete the sentence about energy resources. The Sun is the source of energy for all our energy resources except nuclear, … and tidal. [1] (b) (i) Describe, in terms of molecules, how the steam exerts pressure on the walls of the boiler. … … … … [2] (ii) The steam in the boiler has a constant volume. State what happens to the pressure of the steam if the temperature of the steam is increased. … [1] (c) The power station uses an alternating current (a.c.) generator to generate electricity. Fig. 12.2 shows a simple a.c. generator. direction of rotation S coil N output potential difference Fig. 12.2 (i) Describe how a simple a.c. generator produces an output potential difference (p.d.). … … … … … [2] (ii) The generator converts kinetic energy into electrical energy. The efficiency of the generator is 75%. Calculate the kinetic energy required to produce 3600 J of electrical energy. kinetic energy = … J [2] (d) The fuel rod contains uranium-235 (23592U). Uranium-235 decays by alpha emission. Use correct nuclide notation to complete the decay equation for uranium-235. 235 … … 92U … Th + … α [2] [Total: 11]

11 marks

Mark scheme: 12(a)(i) (nuclear) fission ; 1 12(a)(ii) geothermal ; 1 12(b)(i) molecules (of steam) collide with the walls / container ; 2 (collisions) exert a force (on the walls) ; 12(b)(ii) increases ; 1 12(c)(i) rotating coil experiences a changing magnetic, field / flux ; 2 (output p.d.) is induced / reference to electromagnetic induction ; 12(c)(ii) evidence of (KE / input energy) = output / efficiency  100 or 3600 / 75 100 ; 2 4800 (J) ; 12(d) 235 231 4 2 92 U → 90Th + 2  thorium correct ; alpha correct ;

This question in 0654/43 Oct/Nov 2024

5 Water exists in the solid, liquid or gas state. The particles are arranged differently in each physical state. (a) Name the state where the water particles are furthest apart. … [1] (b) Describe what happens to the movement of water particles during melting. … … … [2] (c) A student takes some ice out of the freezer and leaves it in a beaker in a warm room. Fig. 5.1 shows how the temperature in the beaker changes. temperature in the beaker / °C time / minutes Fig. 5.1 (i) Label the part of the graph where the ice is melting with the letter X. [1] (ii) Describe how Fig. 5.1 shows that the ice is pure rather than a mixture. … … [1] (d) Domestic water is treated so that it is pure enough to drink. Draw one line from each treatment to show why it is used. treatment why it is used chlorination to remove solids sedimentation to remove tastes and filtration and odours use of carbon to kill microbes [2] (e) Water, H2O, is a simple covalent molecule. (i) Complete the dot-and-cross diagram in Fig. 5.2 to show the bonding in water. Only show the outer-shell electrons. O H H Fig. 5.2 [2] (ii) Explain why pure water is a poor conductor of electricity. … … [1] [Total: 10]

10 marks

Mark scheme: 5(a) gas ; 1 5(b) any two from : 2 idea that the movement changes from vibrating about fixed positions ; to moving around each other ; particles move faster ; 5(c)(i) 1 X ; 5(c)(ii) any one from : 1 idea that there is a horizontal part to the graph ; (pure substance) melting occurs at one temperature / a mixture melts at more than one temperature ; 5(d) 2 ;; 5(e)(i) 2 ;; 5(e)(ii) idea that pure water does not contain any free (moving) electrons / ions ; 1

This question in 0654/41 May/June 2025

10 (a) A sealed syringe contains a sample of gas as shown in Fig. 10.1. syringe 5 sealed tip 10 15 gas 20 cm3 Fig. 10.1 (i) State, in terms of particles, what causes pressure of a gas. … … … [2] (ii) The gas in the syringe is heated. State the change, if any, to the average speed of the particles. … [1] (iii) The volume of the gas is kept constant as it is heated. Explain, in term of particles, why the pressure of the gas increases. … … … [2] (b) (i) State the name of the state of matter in which sound travels fastest. … [1] (ii) Ultrasound waves can be used to produce images of unborn babies inside the human body, as shown in Fig. 10.2. skin ultrasound source and detector unborn baby Fig. 10.2 State the lowest frequency of ultrasound waves. … [1] (iii) A pulse of ultrasound is sent into a person from an ultrasound source at the surface of the skin. Ultrasound travels at 1500 m / s inside human bodies. A reflection arrives back at the surface of the skin after 8.0 × 10−5 s. Calculate the depth below the surface at which the reflection was caused. depth = … m [3] [Total: 10]

10 marks

Mark scheme: 10(a)(i) collisions ; 2 between particles and walls (of syringe) ; 10(a)(ii) increases ; 1 10(a)(iii) more frequent collisions ; 2 greater force ; 10(b)(i) solid ; 1 10(b)(ii) 20 000 Hz / 20 kHz ; 1 10(b)(iii) speed = distance / time or v =s / t (in any form) or 1500 = distance / 8.0  10–5 ; 3 distance = 0.12 (m) ; depth = 0.060 (m) ;

This question in 0654/43 Oct/Nov 2025