3 equations. Each page has 10 real-life ramped questions with full FIFA solutions. Every equation is given on the equation sheet in the exam.
Key: C+S = Combined and Separate | S only = Separate Physics only | HT = Higher tier only
- Density: ρ = m/V (C+S)
- Specific latent heat: E = mL (C+S)
- Gases: pV = constant (S only)
Key definitions
Write your answer on paper first, then tap Show answer. Learn the key words – definition questions are quick marks in the exam.
1. What is density? (C+S)
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Mass per unit volume. Unit: kg/m³.
2. Use the particle model to explain why a gas is much less dense than a solid. (C+S)
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In a solid the particles are packed closely together in a regular arrangement. In a gas the particles are far apart, so there is much less mass in the same volume.
3. What is internal energy? (C+S)
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The total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.
4. What happens to the internal energy when a substance is heated? (C+S)
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Heating increases the energy of the particles, so the internal energy increases. This either raises the temperature of the system or produces a change of state.
5. What is specific latent heat? (C+S)
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The amount of energy required to change the state of 1 kg of a substance with no change in temperature.
6. What is the difference between specific latent heat of fusion and of vaporisation? (C+S)
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Fusion: change of state from solid to liquid. Vaporisation: change of state from liquid to vapour (gas).
7. What is the difference between specific heat capacity and specific latent heat? (C+S)
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Specific heat capacity is the energy needed to raise the temperature of 1 kg by 1 °C. Specific latent heat is the energy needed to change the state of 1 kg with no change in temperature.
8. Why is a change of state called a physical change? (C+S)
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Because it is reversible: if the change is reversed, the material recovers its original properties. Mass is conserved during a change of state.
9. How do gas particles create pressure on the walls of a container? (C+S)
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The particles are in constant random motion and collide with the walls. Each collision exerts a force on the wall; the total force per unit area is the gas pressure.
10. How is the temperature of a gas related to its particles? (C+S)
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The temperature of a gas is related to the average kinetic energy of its particles. The higher the temperature, the faster the particles move on average.
11. Explain why the pressure of a gas in a sealed container increases when it is heated (constant volume). (C+S)
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The particles gain kinetic energy and move faster, so they hit the walls more often and with more force. This increases the force per unit area, so the pressure increases.
12. Explain why the pressure of a gas increases when its volume is decreased at constant temperature. (S only)
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The same number of particles are in a smaller space, so they collide with the walls more often. The particles’ speed stays the same (same temperature), but the more frequent collisions mean a greater force per unit area, so the pressure increases.
13. Why does the temperature of air in a bicycle pump rise when it is pumped quickly? (S only, HT)
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Work is done on the gas when it is compressed. This transfers energy to the gas, increasing its internal energy, so its temperature increases.
