AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Internal energy
Internal energy · Particle model of matter · Lesson 3 of 6 · 14 marks · 15 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 STATE (2 marks)
What is meant by the internal energy of a system?
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(Total for Question 1 = 2 marks)
Question 2 EXPLAIN (3 marks)
A beaker of water is heated. Explain what happens to the energy stored within the water and to its temperature.
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(Total for Question 2 = 3 marks)
Question 3 CALCULATE (3 marks)
Calculate the energy needed to raise the temperature of 0.50 kg of water from 20 °C to 60 °C. Specific heat capacity of water = 4200 J/kg °C.
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(Total for Question 3 = 3 marks)
Question 4 EXPLAIN (2 marks)
1.0 kg of water and 2.0 kg of water are both at 50 °C. Which has more internal energy? Explain your answer.
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(Total for Question 4 = 2 marks)
Question 5 EXPLAIN (4 marks)
Ice at 0 °C is heated and melts to water at 0 °C. Explain what happens to the internal energy and to the temperature during melting.
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(Total for Question 5 = 4 marks)
TOTAL FOR PAPER = 14 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (2 marks)
The total kinetic energy and potential energy of all the particles that make up the system.
• Total of kinetic energy 1 mark
• and potential energy of all the particles 1 mark
Question 2 (3 marks)
Heating increases the energy of the particles, so the internal energy increases. The kinetic energy of the particles increases, so the temperature rises.
• Internal energy increases 1 mark
• Particles gain kinetic energy 1 mark
• Temperature rises 1 mark
Question 3 (3 marks)
0.50 × 4200 × 40 = 84 000 J
• Temperature change 40 °C 1 mark
• Correct substitution 1 mark
• 84 000 J 1 mark
Question 4 (2 marks)
2.0 kg, because it has twice as many particles at the same average kinetic energy, so its total energy is greater.
• 2.0 kg of water 1 mark
• More particles so more total energy 1 mark
Question 5 (4 marks)
The internal energy increases because energy is supplied. The energy increases the potential energy of the particles as bonds are weakened, but does not increase their average kinetic energy, so the temperature stays the same.
• Internal energy increases 1 mark
• Potential energy of particles increases 1 mark
• Kinetic energy does not increase 1 mark
• Temperature stays constant 1 mark