levo
Log inStart

Thermal Physics

Internal energy

  • 3 things to know
  • Component 1

Overview

Recall questions on the definition of internal energy as the sum of the random kinetic and potential energies of the particles, why it is a property of the state rather than of a process, what changes it, and how it differs for an ideal gas from a real one.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Define the internal energy of a system.

Key term

Which part of the internal energy of a substance depends on the separation of its molecules?

Key term

Which part of the internal energy of a substance depends on the temperature?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define the internal energy of a system.

    Model answer

    The internal energy of a system is the sum of the random kinetic energies and the potential energies of all its molecules.

  2. 2

    Which part of the internal energy of a substance depends on the separation of its molecules?

    Model answer

    The potential energy contribution depends on the separation, because it arises from the forces the molecules exert on one another.

  3. 3

    Which part of the internal energy of a substance depends on the temperature?

    Model answer

    The random kinetic energy contribution depends on the temperature, since the mean molecular kinetic energy rises with the thermodynamic temperature.

  4. 4

    Why is the kinetic energy of a moving car not part of the internal energy of the car?

    Model answer

    Internal energy counts only the random motion of the molecules relative to the body, whereas the car's kinetic energy comes from the ordered motion of the whole body.

  5. 5

    Explain why melting a solid at its melting point increases the internal energy without changing the temperature.

    Model answer

    The energy supplied goes into separating the molecules against their mutual attraction, so the molecular potential energy rises while the mean kinetic energy, and therefore the temperature, stays the same.

  6. 6

    Explain why the internal energy of a real gas rises when it expands at constant temperature.

    Model answer

    The molecules move further apart against their weak mutual attractions, so their potential energy increases while their mean kinetic energy is unchanged.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Basic Physics
Kinematics
Dynamics
Energy Concepts

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The wires .
attractrepeltwist

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe equation is pV = NkT.
BThe pressure, p, is in Pa.
CThe volume V is in m³.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

The joule is a unit of energy.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Thermal Physics, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a monthSee how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.