Total marks: 100 · Duration: 105 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 100.
- 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 Physics topics 4.1 to 4.4: 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 transfers (12 marks)
(a) A car of mass 1200 kg travels at 15 m/s. Calculate its kinetic energy. [2 marks]
(b) A ball of mass 0.50 kg is lifted 2.0 m above the ground. Calculate the gain in its gravitational potential energy. [2 marks]
(c) The ball is dropped. Ignoring air resistance, calculate its speed just before it hits the ground. [3 marks]
(d) A spring with a spring constant of 40 N/m is stretched by 0.15 m. Calculate the elastic potential energy stored. [2 marks]
(e) An electric motor transfers 1800 J of useful energy for every 2400 J supplied.
(i) Calculate the efficiency of the motor. [2 marks]
(ii) The motor transfers the 1800 J of useful energy in 6.0 s. Calculate its useful power output. [1 mark]
Question 2 — Energy resources and specific heat capacity (14 marks)
(a)* A country plans to replace a gas-fired power station with a wind farm that has the same maximum power output.
Evaluate the advantages and disadvantages of this change. [6 marks]
(b) A student uses a 50 W electric heater to heat a 1.0 kg aluminium block for 600 s. The temperature of the block rises by 30 °C.
(i) Calculate the specific heat capacity of aluminium from these results. [3 marks]
(ii) The accepted value is 900 J/kg °C. Explain why the student's value is higher. [2 marks]
(iii) Suggest one improvement that would make the student's value closer to the accepted value. [1 mark]
(c) Explain why houses with thicker walls made of material with a lower thermal conductivity cool down more slowly. [2 marks]
Question 3 — Circuits (14 marks)
(a) A current of 0.40 A flows through a lamp for 2.0 minutes. Calculate the charge that flows. [2 marks]
(b) A 4.0 Ω resistor and an 8.0 Ω resistor are connected in series to a 12 V battery.
Calculate the current in the circuit and the potential difference across the 8.0 Ω resistor. [3 marks]
(c) A 6.0 Ω resistor and a 3.0 Ω resistor are connected in parallel across a 6.0 V supply.
(i) Calculate the current in each resistor and the total current from the supply. [2 marks]
(ii) Explain why the total resistance of two resistors in parallel is less than the resistance of the smaller resistor. [2 marks]
(d) (i) Describe how the resistance of a light-dependent resistor (LDR) changes as the light intensity increases. [1 mark]
(ii) Give one use of a thermistor. [1 mark]
(e) Explain why the current–potential difference graph for a filament lamp is not a straight line. [3 marks]
Question 4 — Domestic electricity (12 marks)
(a) Give the frequency and the potential difference of the UK mains supply. [2 marks]
(b) Explain how the earth wire protects someone using a metal-cased kettle if a fault makes the case live. [2 marks]
(c) A kettle has a power of 2.3 kW and is connected to the 230 V mains. Calculate the current. [2 marks]
(d) Calculate the energy transferred by the kettle in 3.0 minutes. [2 marks]
(e) Explain how the National Grid uses step-up transformers to reduce energy losses in transmission cables. [3 marks]
(f) A current of 2.0 A flows through a 5.0 Ω resistor. Calculate the power transferred. [1 mark]
Question 5 — Static electricity (6 marks)
(a) A polythene rod is rubbed with a cloth and becomes negatively charged. Explain how it becomes charged. [2 marks]
(b) A spark can jump from a highly charged object to an earthed conductor nearby. Explain, in terms of the electric field, why this happens. [2 marks]
(c) A charged balloon sticks to an uncharged wall. Explain why. [2 marks]
Question 6 — The particle model (14 marks)
(a) A metal block measures 2.0 cm × 3.0 cm × 4.0 cm and has a mass of 0.054 kg. Calculate its density in kg/m³. [3 marks]
(b) Describe how a student could measure the volume of an irregularly shaped stone. [2 marks]
(c) Calculate the energy needed to melt 0.20 kg of ice at 0 °C. (Specific latent heat of fusion of ice = 334 000 J/kg) [2 marks]
(d) Explain why the temperature of the ice stays at 0 °C while it is melting, even though energy is being supplied. [2 marks]
(e) A sealed container of gas is heated. Its volume does not change. Explain, in terms of particles, why the pressure of the gas increases. [3 marks]
(f) A gas at a pressure of 100 kPa has a volume of 2.4 m³. It is compressed to 0.60 m³ at constant temperature. Calculate the new pressure. [2 marks]
Question 7 — Atomic structure and radioactivity (16 marks)
(a) What is meant by isotopes? [1 mark]
(b) Describe the penetrating power of alpha, beta and gamma radiation. [3 marks]
(c) (i) Radium-226 (atomic number 88) decays by alpha emission to form radon. Give the mass number and atomic number of the radon nucleus. [2 marks]
(ii) Carbon-14 (atomic number 6) decays by beta emission. Give the mass number and atomic number of the new nucleus, and name the element formed. [2 marks]
(d) The activity of a radioactive sample falls from 800 Bq to 100 Bq in 24 hours. Calculate the half-life. [2 marks]
(e) Explain the difference between irradiation and contamination. [2 marks]
(f) Describe the difference between nuclear fission and nuclear fusion. [2 marks]
(g) A radioactive tracer is injected into a patient. Explain why the tracer should emit gamma radiation and have a short half-life. [2 marks]
Question 8 — Investigating the resistance of a wire (12 marks)
(a)* Describe a method to investigate how the length of a wire affects its resistance. [6 marks]
(b) The student's results show a resistance of 0.80 Ω for 20 cm of wire and 1.60 Ω for 40 cm. Calculate the resistance per metre of the wire. [2 marks]
(c) When the student plots resistance against length, the line does not pass through the origin. Suggest a reason. [2 marks]
(d) Explain why the student should switch off the circuit between readings. [2 marks]