CONCEPTS ABOUT HEAT

OLD CONCEPT OF CLASSICAL PHYSICS :

Upto the begening Century the heat is called "A weightless fluid called coloric which is present in every material body and only emits out of a substance when it is being cut or burnt"

After some years the fluid concept is challanged by Count Rumford.

He made an experiment in order to broke that concept of classical physics he take a cannon barrels and a very dull drill and tried to cut that but it not cut but it is very heated so the concept that the (heat is only emit out of a substance when it is being cut or burnt) was discarded.There become a little Difference in the defination of heat that:
"the heat is emit out of a substance when the machenical work or pressure is in progress"

 MODERN CONCEPT :

In 19th Century the heat is defined as:

"The HEAT is a form of ENERGY that transfers from the hot body to a cold body"

When a hot body get in thermal contact with the cold body the heat transfers from the hot body to the cold body and the cold body absorbs the heat and then the heat is converted to its Internal Energy.

Internal Energy:

"It is the Sum of microscopic kinetic and Potential Energies of the molecules of the system"