Heat vs Temperature

Quick Answer

Heat is energy in transit between bodies at different temperatures. Temperature is the average kinetic energy of the particles in a body.

What Each One Really Means

This one is very important because everyday English has destroyed it for many people. In normal conversation, if something is hot, we say it has heat. But in thermodynamics, that sentence is wrong. An object cannot contain heat. Heat is energy in motion, moving from a hotter body to a colder one because of a temperature difference. The moment the transfer stops, there is no heat anymore, only internal energy. Temperature, on the other hand, is a measurement. It tells you the average kinetic energy of the particles. Notice the word average. This is why a cup of boiling water can have a higher temperature than a swimming pool, but the swimming pool contains far more internal energy. More particles, more total energy, even if each particle is moving slower. I always ask my students: if you put a small hot nail into a big bucket of cold water, which one has more heat? They always hesitate. The correct way to think is that heat is not a thing that either one owns. It is the flow between them. Once you understand that heat is a process and temperature is a state, the whole of thermodynamics becomes easier. The sign conventions also make sense now. Heat entering a system is positive. Heat leaving is negative.

Side-by-Side Comparison

Memory Device

Heat is a verb disguised as a noun. It is doing something. Temperature is a noun. It just is.

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