10 Thermodynamics

Professor George Smoot's Physics 10 Class

Laws of Thermodynamics

• Zeroth: If two objects are in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

• First Law: The change in internal energy (U) of a system is equal to the net heat (Q) added plus the work (W) done on the system.
  DU = Q + W
  (Conservation of Energy)

• Second Law:

  The Principle of Thomson: It is impossible, by a cyclic process, to take heat from a reservoir and convert it into work, without in the same operation, transferring heat from a hot to a cold reservoir.

  The Principle of Clausius: It is impossible to transfer heat from a cold to a warm reservoir without, in the same process, converting a certain amount of work into heat.

  Any device is less than 100% efficient.

  The Entropy of a system tends to increase.

• Third Law:Absolute zero may be approached, but never reached.

  Nernst Theorem: Entropy is zero at absolute zero.