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

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

Instructions to candidates

Answer all questions in the spaces provided.
You are expected to use a calculator. Some equations are given; others must be recalled.
This paper covers Topics 18–21: Energy, Electricity, Particle Model of Matter, and Atomic Structure.
The maximum mark for this paper is 70. The marks for each question are shown in brackets.

Paper

Section A — Multiple Choice (5 marks)

1. The unit of power is the: (1 mark) A) joule B) watt C) newton D) volt

2. In a series circuit, the current is: (1 mark) A) the same everywhere B) shared between components C) zero D) largest at the battery

3. Which energy store increases when an object is lifted higher? (1 mark) A) Kinetic B) Elastic potential C) Gravitational potential D) Thermal

4. Which radiation is stopped by a sheet of paper? (1 mark) A) Alpha B) Beta C) Gamma D) X-ray

5. Density is calculated using: (1 mark) A) mass × volume B) mass ÷ volume C) volume ÷ mass D) mass + volume

Section B — Structured Questions (47 marks)

6. Energy is transferred in a falling object. (a) Name the main energy transfer as a ball falls (ignoring air resistance). (1 mark) (b) Calculate the kinetic energy of a 0.5 kg ball moving at 4 m/s. (Eₖ = ½mv²) (2 marks) (c) State the principle of conservation of energy. (1 mark) (d) Explain one way the unwanted energy transfer (dissipation) in a machine can be reduced. (2 marks)

7. A kettle is connected to the mains. (a) State the potential difference and frequency of the UK mains supply. (2 marks) (b) The kettle is rated at 2300 W. Calculate the energy transferred in 90 s. (E = Pt) (2 marks) (c) Explain the function of the earth wire and fuse together in keeping the kettle safe. (3 marks)

8. A student investigates resistance. (a) State Ohm's law as an equation. (1 mark) (b) Calculate the resistance of a component when a current of 0.5 A flows at a potential difference of 6 V. (2 marks) (c) Describe how the resistance of a thermistor changes with temperature. (1 mark) (d) Explain why the resistance of a filament lamp increases as the current increases. (2 marks)

9. The particle model explains states of matter. (a) Describe the arrangement and movement of particles in a gas. (2 marks) (b) Define specific heat capacity. (2 marks) (c) Calculate the energy needed to raise the temperature of 2 kg of water by 10 °C. (c = 4200 J/kg°C) (2 marks) (d) Explain why the temperature stays constant while a substance is melting. (2 marks)

10. Atoms can be radioactive. (a) Describe the structure of an atom in terms of the nucleus and electrons. (2 marks) (b) Name the three types of nuclear radiation in order of increasing penetrating power. (2 marks) (c) A radioactive isotope has a half-life of 2 days. A sample has an activity of 1600 Bq. Calculate its activity after 6 days. (2 marks)

Section C — Extended Response

11. Describe how the model of the atom changed from the "plum pudding" model to the nuclear model, and explain the evidence that led to this change. (6 marks)

Mark Scheme

Section A: 1. B; 2. A; 3. C; 4. A; 5. B. (5)

6 (a) gravitational potential → kinetic (1). (b) ½ × 0.5 × 4² = ½ × 0.5 × 16 = 4 J (1 method, 1 answer). (c) energy cannot be created or destroyed, only transferred/stored/dissipated (1). (d) lubrication reduces friction (1) so less energy wasted as heat (1) [or insulation]. (6)

7 (a) 230 V (1); 50 Hz (1). (b) E = 2300 × 90 = 207 000 J (1 method, 1 answer). (c) a fault makes the case live (1); a large current flows to earth (1); melting the fuse and breaking the circuit (1). (7)

8 (a) V = I × R (1). (b) R = V ÷ I = 6 ÷ 0.5 = 12 Ω (1 method, 1 answer). (c) resistance decreases as temperature increases (1). (d) the filament gets hotter (1); ions vibrate more, so resistance increases (1). (6)

9 (a) far apart (1); fast, random motion (1). (b) energy to raise the temperature of 1 kg of a substance by 1 °C (2). (c) ΔE = mcΔθ = 2 × 4200 × 10 = 84 000 J (1 method, 1 answer). (d) energy is used to overcome forces between particles / change state (1), not to raise kinetic energy/temperature (1). (8)

10 (a) small dense nucleus of protons and neutrons (1); electrons in shells around it (1). (b) alpha, beta, gamma (1 for naming all three, 1 for correct order) — increasing penetration. (c) 6 days = 3 half-lives; 1600 → 800 → 400 → 200 Bq (1 for 3 half-lives, 1 answer). (6)

11 — Levels (6): Indicative: plum pudding model = ball of positive charge with electrons embedded. Alpha scattering experiment: alpha particles fired at thin gold foil; most passed straight through (atom mostly empty space); a few deflected or bounced back (small, dense, positively charged nucleus). This evidence could not be explained by the plum pudding model, leading to the nuclear model.

L3 (5–6): Describes both models and the scattering evidence with correct conclusions.

L2 (3–4): Some description of the experiment/observations.

L1 (1–2): Simple statements.

Sample Answers with Examiner Commentary

Question 11 — Sample Answers

Grade 9 answer "In the plum pudding model the atom was a ball of positive charge with negative electrons embedded in it. In the alpha particle scattering experiment, positively charged alpha particles were fired at very thin gold foil. Most passed straight through, showing the atom is mostly empty space. A small number were deflected through large angles, and a few bounced straight back, showing there must be a tiny, dense, positively charged nucleus that repelled them. The plum pudding model could not explain these deflections, so it was replaced by the nuclear model, in which the mass and positive charge are concentrated in a central nucleus." Mark: 6/6. Examiner commentary: Both models described, all three observations linked to the correct conclusions, and the reason for the change is explicit. Top band.

Grade 6 answer "They fired alpha particles at gold foil. Most went through but some bounced back, which showed there was a small nucleus in the middle that was positive. This was different from the plum pudding model." Mark: 4/6. Examiner commentary: Correct observations and conclusion about the nucleus, but the plum pudding model itself is not described and "mostly empty space" is not stated explicitly. Adding those reaches the top band.

Question 9(c) — Sample Answers

Grade 9 answer "ΔE = m × c × Δθ = 2 × 4200 × 10 = 84 000 J." Mark: 2/2. Examiner commentary: Correct equation, substitution and answer with the unit.