what is heat (energy)?

Answer 1

There seems to be an awful lot of confusion between the meanings of heat and of temperature!
Temperature is indeed a measure of the kinetic energy stored by molecules, but 'heat' is the name given to the transfer of energy due to a temperature difference. To be strictly correct, 'heat' is not of itself energy, rather it is the name given to the TRANSFER of energy. e.g. you can store the bus (energy) but you can't store the bus journey (heat).

Answer 2

Heat energy is actually kinetic energy at the molecular level.
E.g. When water is heated and its temperature rises from 20 degrees to 30 degrees, what has actually happened is that the water molecules have gained kinetic energy from the heater or fire and are now moving more energetically.

Answer 3

You've sortta answered your own question :)
Heat is a manifestation of an objects energy - temperature is basically a measure of kinetic energy.
Of course if you want to go deeper into the subject, then you're getting into some pretty heavy physics ;)

Answer 4

They say heat is simply the measure of speed of moving particles, but it seems to make more sense to me that whatever heat is is causing the particles to move. Maybe it's what fills up the empty space inside an atom.

Answer 5

Heat (Temperature) is a measurement of how fast particles are moving. That is all it is. All forms of energy all basiclly motion.

Answer 6

Basically motion. When you heat up a gas the molecules go faster.

Answer 7

It's the vibrational and kinetic engery pocessed by a molecule / atom / subatomic particle.

Answer 8

is doing work done by sun and other heat sources

Answer 9

http://en.wikipedia.org/wiki/Heat