# Confused with heat as a form of energy [duplicate]

I have quite a simple question. Energy can be defined as capacity to do work.

When energy is exchanged between thermodynamic systems by thermal interaction, the transfer of energy is called heat.

I can't understand what is the work done. For example, what is the work done in cooling water from 20 to 40 celsius (1 atm)?

So, is heat a form of energy if energy is capacity to do work?

## marked as duplicate by Chris♦, Martin Beckett, Kyle Kanos, Jon Custer, PulsarMay 5 '18 at 2:42

• heat is the transfer of energy, generally from one substance to another. It is not a form of energy. "Heat" in physics is different from the thermal energy of an object – Martin Beckett May 3 '18 at 4:31
• @MartinBeckett Yes but if energy is capacity to do work, it is not heat – santimirandarp May 3 '18 at 4:32
• If you heat up that water bottle, if will expand (slightly). Expansion is potential work done. – Steeven May 3 '18 at 7:51

• Are you referring to this equation: $Q=cm\Delta T$? – Steeven May 3 '18 at 7:53