Thermal Energy Transfer

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Internal Energy

Internal energy is the sum of the randomly distributed kinetic energies and potential energies of all the particles in a gas.

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Particle energies

  • Kinetic energy comes from the random movements of particles in a gas.
  • Potential energy comes from the interactions between the particles.
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Adding energy

  • The internal energy can be increased by adding energy to the system.
  • If you add heat to a system it increases in energy but NOT always in temperature.

Specific Heat Capacity

The specific heat capacity is the amount of energy needed to raise one kilogram of material by 1 degree Kelvin.

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Heat capacity

  • Energy required = mass x specific heat capacity x change in temperature
    • Q=mcΔθQ=mc{\Delta\theta}
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  • All temperatures should be calculated in Kelvin.
    • For changes in temperature, the change in degrees is the same as the change in Kelvin.

Specific Latent Heat

The energy required to change the state of an object is the specific latent heat.

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Changing state

  • To make an object go from a solid to a liquid or a liquid to a gas you need to add some energy. This energy is the latent heat.
  • The energy goes into weakening the intermolecular bonds NOT into changing the temperature. The equation for the energy is:
    • The energy needed = mass x specific latent heat
    • Q=mlQ=ml
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Kinetic energies

  • When the latent heat is added to a solid to melt it, the bonds between molecules are weakened.
  • Because all of the energy goes into weakening the bonds, there is no gain in kinetic energy and there is no gain in temperature.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

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