What is temperature? This inquiry comes up rather a bit—especially in introductory science courses. The most typical answer is something favor this:

Temperature is a measure up of the mean kinetic power of the particles in an object. As soon as temperature increases, the motion of these particles likewise increases.

You are watching: The average kinetic energy of particles in an object

It's no a terrible definition, yet it's not the ideal either. There space plenty of other crazy things about temperature the you should more than likely know.


If temperature is a measure of the mean kinetic energy, shouldn't thermal energy and also temperature it is in the same thing? No. Thermal energy is the complete energy things has as result of the internal motions that its particles. The temperature is regarded the average kinetic energy—not the total kinetic energy.


Here's a classic example the you can shot at home. Placed a item of cold pizza on peak of a paper of aluminum foil and also then stick that in the oven to heat up. After around 10 minutes, the pizza have to be nice and also hot—the aluminum foil is the about the very same temperature. You have the right to pull the aluminum foil out through your fingers, but not the pizza. Return the aluminum foil has actually a high temperature, its short mass means it doesn't have actually much thermal energy. Without a most thermal energy in the foil, your fingers won't gain burned. Meaning? thermal energy and also temperature are different things.


More interpretations of Temperature?

You already have one meaning from above, however I to be going to give you two much more definitions. The an initial one is the historic version. It goes like this:


Temperature is the quantity that 2 objects have in common after being in call for a long time.


This meaning is based on the idea of thermal equilibrium. If you put an aluminum ball right into some water, at some point the water and also the ball will have the same temperature. They won't have the same thermal energy, however they will have actually the very same temperature. It's a an extremely operational meaning of temperature—and that's not a poor thing.


But really, this temperature is the basis of many thermometers. Take it your an easy mercury or alcohol thermometer (the mercury ones room not so common because—you know, lock contain mercury). As soon as you put this thermometer in a liquid or miscellaneous else, the temperature the the liquid within the thermometer transforms until it is the exact same as the object. Because both mercury and alcohol increase with boost in temperature, you deserve to determine the temperature based upon this thermal development (or contraction). Really, you can say that the thermometer also came prior to the idea the temperature.

Now for the second an interpretation of temperature. This one is nice tough, so host on to something.

Temperature is the price that interior energy transforms with respect to entropy.

It's short, yet there's a lot of in there. First, what is entropy? ns could try to define entropy, however this would certainly be a complete brand-new blog post. Instead, you can just examine out this an extremely awesome post by Aatish Bhatia in which he describes entropy making use of sheep. Yes, it's really good.

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So, rather of a complete explanation the entropy, I will certainly just give some interesting aspects of it. Thermal equilibrium is no a purely energy phenomena. Energy is conserved as soon as two objects reach thermal equilibrium, however it would likewise be satisfied if one object gained hot and also the various other one ended up being cold. Heat equilibrium is a statistics process. It just so happens that the most probable outcome for 2 objects in call is that they reach the same temperature. The other weird situations (one getting hot and also one gaining cold) can additionally technically happen, however their opportunities are way less than you winning the lottery (and your opportunity of win the lottery is essentially zero).