Heat
Heat like
work, is a form of energy.
The energy transfer between a system and its surroundings is called
heat if it occurs by virtue of the
temperature difference across the boundary.
The two modes of energy transfer – work and heat- depend on the
choice of the system. Heat energy moves from a hotter body to a colder body
upon contact of the two bodies.
If two bodies at different temperatures are allowed to
remain in contact, the system of two bodies will eventually reach a thermal
equilibrium (they will have the same temperature).
A body never contains heat. Rather heat is a transient phenomenon
and can be identified as it crosses the boundary.