eli5: What exactly is temperature?

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I understand something like equilibrium in a cell functions to make sure that the conditions outside and insider are as similar as possible. However, how does the transfer of temperature work between two objects? Why is it that if you put a cold object on a hot one, the cold one gets warmer and the hot one gets cooler? If temperature isn’t a physical thing, then how does it work?

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2 Answers

Anonymous 0 Comments

Think of temperature as energy. Imagine the molecules of an item as a ball pit. Sitting still the item is cold as it has no energy and the balls aren’t moving. Now imagine a bunch of balls rapidly vibrating around. That’s heat. Now what happens if those vibrating balls collide with the “cold” balls that are sitting there? The “hot” balls hit the “cold” balls and transfer some energy. Now the “hot” ball is moving slower and the “cold” ball is moving around more. That happens more and more until the temperatures equalize.

Anonymous 0 Comments

Temperature is the average kinetic energy of the molecules in a substance. KE = 3/2 kT. k is the boltzmann constant and T is the temperature in kelvin. When something hot is placed next to something cold, the hot molecules with more kinetic energy when slamming into the cold ones, transfer some of that kinetic energy, thus cooling down the hot object and heating up the cold one, and then boom, you have thermal conduction. Once everything in a system has about the same kinetic energy, everyrhing is the same temperature. It’s very unlikely that a few molecules will spontaneously get a significant portion of the energy available. The whole system wants to be the same, it’s the 3rd law of thermodynamics.