Heat is internal energy that is exchanged between two objects due to their difference in temperature.
Heat always transfers, or flows, from a body at higher temperature to one at lower temperature.
This is an expansion of the Work-Energy Theorem.
Now we will call it the First Law of Thermodynamics. Heat is just another form of energy and energy is (still) conserved.
W + Q = Etot = KE + PE + Eint
1 cal = 4.186 J
1 BTU = 1054.8 J
1 "food Calorie" = 1 Cal = 1 kcal = 1000 cal
(c) 2005, Doug Davis; all rights reserved
Zeroth Law Conduction Return to ToC, Temperature