Internal energy — AQA GCSE Physics
Test yourself on Internal energy with AQA GCSE practice questions.
7 days Premium · Then free forever · No card, no charge
Internal energy explained
Heating transfers energy into a system, and that energy ends up with the particles.
Read the full explanation
Which part of their energy rises depends on what the substance is doing. While the temperature is rising, the extra energy goes to the kinetic store, so the particles vibrate or move faster and their mean kinetic energy increases. While the substance is changing state, the temperature holds constant and the extra energy goes to the potential store instead, weakening the attractions that hold the particles close together, so their potential energy increases while their kinetic energy stays the same. Either way the internal energy of the system increases, because the energy is not lost, only stored differently.
Your focus
- Predict what happens to the kinetic and potential energies of the particles as a substance melts at constant temperature.
- Explain where the energy goes when a substance is heated and its temperature rises.
- Describe the change in internal energy of a system during heating, naming both contributions.
Internal energy exam tips
Marking Points
- one mark for heating increasing the energy of the particles in the system
- one mark for the mean kinetic energy of the particles increasing while the temperature rises
- one mark for the potential energy of the particles increasing during a change of state
- one mark for the kinetic energy of the particles staying the same while a substance melts at constant temperature
Examiner Tips
- 💡Check the temperature first, because constant temperature means potential energy and rising temperature means kinetic energy.
- 💡In tick-box questions with a row for kinetic and a row for potential, give one tick per row only.
- 💡Write 'mean kinetic energy' rather than 'speed' when describing a whole system of particles.
Common Mistakes
- saying the particles move faster while a substance melts, even though the temperature is constant
- stating that the potential energy of the particles decreases as a solid melts
- claiming the particles expand or gain mass when they are heated
- treating a constant temperature as evidence that no energy is being transferred in