"Work" and "heat" are commonly used words in everyday life. But they mean very specific things in the physics field of thermodynamics.
Hey everyone, in this (rather short) video I wanted to discuss the exact definitions of the words "work" and "heat" in a thermodynamic context. These words are very easy to get confused, especially because their definitions have subtleties to them that are difficult to teach and understand.
And then there's the added complexity that these two words are used in day-to-day language to mean very different things to what they mean thermodynamically. So it's important to really nail the definitions right at the outset, before delving more into the world of thermodynamics.
Work in thermodynamics is a specialisation of the physics definition of "work". This is often defined as a force x a distance moved by the force, but in thermodynamics it refers to the energy transferred to / from the system, in a way that involves the presence of detectable macroscopic (large scale) forces. Other energy transfers certainly involve microscopic (small scale) forces, but for an energy transfer to be defined as work, large scale forces must exist.
Heat is the other kind of energy transfer - one where NO large scale forces are involved (assuming we're dealing with a closed system). In other words, assuming our system is not exposed to the external environment, any energy transfer that is not work, must be heat by definition.
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10 июл 2024
