Question

why heat is a form of energy

Answer 1

Yes, we consider heat as a form of energy. because when fire or combustion takes place some amount (that may be large amount or small) of energy (exothermic) gets released. so we consider heat as a form of energy.

Answer 2

Heat is a form of energy because it can neither be created nor be destroyed, it can only be transfered from one surface to another. Heat make the things hot and hence we can also use it for doing work. so it is a form of energy.