It's that time again, my imaginary friends, for coffee and heat science. I wanted to talk about the three laws and improve my knowledge on that, but I keep forgetting about entropy. Specifically, I forget the level of math that goes into it and the depth that goes into that topic. So I'll talk about the Zeroth and First law today, and start in on the insanity that is entropy next time.
The Zeroth Law is the basics. When you read about this stuff, this law sometimes isn't even stated, but it's always implied. It's good to have an understanding of it, so here it goes.
Cold is the lack of energy. Heat is energy. Energy moves to where there is no energy, heat travels towards the cold. In the case of heat, it will move back in forth between two states until they reach equilibrium; which is to say, until they're both the same temperature. Think hot tea with an ice cube. The heat of the tea transfers to the ice cube, which in turn cools the tea, and they both reach equilibrium. When they both become the same temperature, they stop transfer. In this case though, they will transfer heat with air if it's at a different temperature. Without that explanation, think if two things have equal temperature, then they are in equilibrium. Or A=B, therefore, equilibrium. According to transitive logic, if B=C, then A=C. I hope all my imaginary friends are mathematicians, and only pay attention to those last two lines.
Ugh. I've just developed pity for every teacher I've had. But right now, I'm not going to dwell on it, and I'm just going to move on.
The First law of Thermodynamics is the conservation of energy principle. This actually has a place near and dear to my heart because it was the first thing I saw outside of school that applied to physics. The principle states that energy can't just be magicked out of thin air, and when it's done it doesn't just disappear. No, energy transform into other energy. I had a teacher that always added "And it commonly becomes heat energy." I helped move hay bales as a summer job back in high school. When bales get wet, you have to keep them in the field for 72 hours, then separate them from the dry bales. The microboes and bacteria inside the bale are creating a lot of energy. Try this: if you have a compost pile, stick your hand in the middle of it. Or you can trust me that it's hot. Same thing with the hay bales. So, if you keep them with the dry bales, there's a chance it will start a barn fire. There is another point of proof of why I am a nerd.
It also states that the change in internal energy of a system is equal to the heat added to said system minus the work done. The internal energy is "the energy associated with the random, disordered motion of molecules." I add heat to the system, in turn the system does work. It makes something move. Any heat not being used for work adds to that random, disordered motion of molecules. This is used extensively for heat engines. And thats a good place to stop, and I'll talk about entropy next time.
The truth is, I enjoy math. I feel like math is a puzzle to solve, and puzzles have always made me happy. The deeper I dive into this, the more comfortable I feel.