Mumbai university > MECH > SEM 3 > THERMO

Marks: 5M

Year: Dec 2014

• The most commonly used temperature scale is centigrade scale, which takes Freezing point of water as 0 and boiling point as 100

• It was later observed by Lord Kelvin that if temperatures can go below 0 0C then it should not be in fact called 0.

• He later, with the help of Carnot theorem, proved that temperature at any point in universe cannot go below -273.150C and hence, this temperature should actually be called 0.

• This temperature was later named as absolute 0 kelvin or 0 K.

• It means that any property of a body related to temperature will also be zero at absolute zero.

• It also means that all bodies have some positive temperature and hence some positive energy.

• Example: specific enthalpy of a gas is directly proportional to its absolute temperature.

  . h α T

  . h= Cp T

  Where Cp = specific heat at constant pressure