AQA GCSE Combined Science: Trilogy — Physics Paper 1 (Higher Tier)

Total marks: 70 · Duration: 75 minutes · Tier: Higher

Instructions to candidates

• Use black ink or black ball-point pen. Draw diagrams in pencil.
• Answer all questions in the spaces provided.
• In all calculations, show clearly how you work out your answer.
• You may use a calculator.
• Where a question describes a circuit, graph or apparatus in words, you may find it helpful to sketch it.

Information

• The maximum mark for this paper is 70.
• The marks for questions are shown in brackets.
• You are expected to use good English and to organise information clearly, especially in questions marked with an asterisk (*).
• This paper covers AQA GCSE Combined Science: Trilogy physics topics 6.1 to 6.4: energy; electricity; the particle model of matter; and atomic structure.
• Take the gravitational field strength g = 9.8 N/kg.
• Equations you may need that are on the AQA Physics equations sheet: elastic potential energy = ½ × spring constant × (extension)²; change in thermal energy = mass × specific heat capacity × temperature change; thermal energy for a change of state = mass × specific latent heat.

Paper

Question 1 — Energy stores and efficiency (9 marks)

A roller coaster car of mass 500 kg is pulled to the top of a slope. It is released from rest and rolls down a vertical drop of 20 m.

(a) Calculate the gravitational potential energy lost by the car as it falls 20 m. [2 marks]

(b) At the bottom of the drop the car's speed is 18 m/s. Calculate its kinetic energy. [2 marks]

(c) Calculate the energy dissipated as the car rolls down the drop. [1 mark]

(d) Calculate the efficiency of the transfer from the gravitational potential energy store to the kinetic energy store. Give your answer as a percentage to 2 significant figures. [2 marks]

(e) At the end of the ride the car is stopped by a spring buffer of spring constant 250 N/m. Calculate the elastic potential energy stored in the spring when it is compressed by 0.08 m. [2 marks]

Question 2 — Specific heat capacity (9 marks)

A student heats a 2.0 kg steel block using a 48 W electric heater placed in a hole in the block. A thermometer in a second hole measures the temperature. The student plots a graph of temperature against time.

(a) Once the temperature starts to rise steadily, the gradient of the graph is 0.050 °C/s.

Calculate the specific heat capacity of steel. [3 marks]

(b) For the first 30 seconds after the heater is switched on, the temperature of the block does not rise. Suggest why. [2 marks]

(c) Later in the experiment the graph starts to curve, and its gradient gets smaller. Explain why. [2 marks]

(d) The heater is connected to a 12 V supply. Calculate the current in the heater. [2 marks]

Question 3 — Energy resources (8 marks)

(a)* The UK is replacing some fossil fuel power stations with a mixture of nuclear power stations and solar farms.

Compare the use of nuclear power and solar power for generating electricity in the UK. [6 marks]

(b) Give two reasons why less electricity is now generated from coal in the UK than in the past. [2 marks]

Question 4 — Circuits (11 marks)

(a) A phone is charged with a current of 1.5 A for 40 minutes. Calculate the charge that flows. [2 marks]

(b) The charging potential difference is 5.0 V. Calculate the energy transferred to the phone by this charge. [2 marks]

(c) A 15 Ω resistor and a 30 Ω resistor are connected in series to a 9.0 V battery.

(i) Calculate the total resistance of the circuit. [1 mark]

(ii) Calculate the current in the circuit. [2 marks]

(d) Two identical lamps are connected in parallel to a 6.0 V supply. State the potential difference across each lamp and explain why one lamp stays lit if the other one breaks. [2 marks]

(e) A thermistor is connected in series with a heater-control unit. The temperature in the room falls.

Describe how the resistance of the thermistor changes, and how this affects the current in the circuit. [2 marks]

Question 5 — Current–potential difference characteristics (7 marks)

(a) Describe how the current–potential difference graph of a resistor at constant temperature differs from the graph for a filament lamp. [2 marks]

(b) A car headlamp has a potential difference of 12 V across it and a current of 2.0 A in it.

(i) Calculate the resistance of the headlamp. [1 mark]

(ii) Calculate the power of the headlamp. [1 mark]

(c) Describe the current–potential difference characteristic of a diode. [2 marks]

(d) Give one reason why LED headlamps are replacing filament headlamps. [1 mark]

Question 6 — Mains electricity and the National Grid (7 marks)

(a) Give the colour of the insulation on the live wire in a UK plug, and the potential difference between the live wire and earth. [2 marks]

(b) A lamp is plugged into a socket and switched off at the lamp. Explain why touching a bare live wire in the cable between the socket and the lamp's switch could still give an electric shock. [2 marks]

(c) A transmission cable has a resistance of 2.5 Ω and carries a current of 400 A. Calculate the power dissipated in the cable. [2 marks]

(d) Explain why step-down transformers are used before electricity reaches homes. [1 mark]

Question 7 — The particle model of matter (10 marks)

(a) A student finds the density of cooking oil. The mass of an empty measuring cylinder is 84.0 g. The student pours in 50.0 cm³ of oil, and the new mass is 129.5 g.

Calculate the density of the oil in kg/m³. [3 marks]

(b) Explain, in terms of particles, why a gas has a much lower density than the same substance as a solid. [2 marks]

(c) A kettle boils off 0.050 kg of water at 100 °C. The specific latent heat of vaporisation of water is 2 260 000 J/kg.

Calculate the energy needed. [2 marks]

(d) What is meant by the internal energy of a substance? [1 mark]

(e) Explain the difference between specific heat capacity and specific latent heat. [2 marks]

Question 8 — Atomic structure and radioactivity (9 marks)

(a) Explain why an atom has no overall charge. [1 mark]

(b) Polonium-210 (atomic number 84) decays by emitting an alpha particle to form an isotope of lead (Pb).

Write the balanced nuclear equation for this decay. [2 marks]

(c) When an atom absorbs electromagnetic radiation, an electron can move to a higher energy level. Explain how absorbing radiation can turn an atom into a positive ion. [2 marks]

(d) The table shows the corrected count rate from a radioactive sample.

(i) Determine the half-life of the sample. [1 mark]

(ii) Express the decline in count rate after 60 minutes as a ratio of the final count rate to the initial count rate. [1 mark]

(e) Explain why it is important for the results of studies on the effects of radiation on people to be published and shared with other scientists. [2 marks]