FIRST LAW OF THERMODYNAMICS

First Law: - If a closed system is undergone in a cyclic process, then mechanical work done is directly proportional to the Heat Transfer.

First Law of thermodynamics



  • Heat and work mutually convertible in a cyclic process.
  • Applicable for reversible as well as irreversible process.
  • For isolated system energy(E) always constant.
  • for an ideal gas, Internal energy depends on temperature only.
  • Follow Conservation of Energy rules.
  • Total energy of a system E = Ep + Ek + U

  • Enthalpy depends only on temperature.
  • First law of thermodynamics furnishes the relationship between Heat, work and properties of the system.
  • First law of thermodynamics was developed by Joule.
  • First law doesn't help to predict whether the system will or not undergo a change.
  • Does not  enable to determine change in entropy.

PMM 1 (Perpetual Motion Machine First Kind): -

There can be no machine which would continuously supply mechanical work without some other form of energy disappearing simultaneously. 
Such a fictitious machine is called Perpetual Motion Machine of the first kind.

  • A machine that continuously creates its own energy.