all right welcome to thermodynamics I don't know what you think of when you think of thermodynamics but thermo I think of heat but it's so I think of heat but it's really energy and dynamics right means changes or it's changing and so thermodynamics we're not not just talking about heat although that is part of it and we're really talking about the energy and the change of energy and also energy can be viewed as the ability to do work you know that work and energy have the same units they are kind of interchangeable sometimes you can convert right energy into work or put work into increase the energy so a few things that we'll be looking at this semester is the energy in heat thermal energy kinetic energy potential energy internal energy then one more flow work we'll talk about a little abstract but it is the work needed for a fluid to flow into and out of a control volume and and then just work we're gonna be looking at all of these how they change we're gonna be keeping track of them adding them how much is going in how much is going out how much do we start with how much do we do begin with but thermodynamics is really the change in the study of energy of a system there's classful and statistical classical is kind of a big picture thermodynamics looking at the macroscopic level looking at the whole fluid you know the fluid as a whole the control volume as a whole instead of statistical is some kind of looking at individual articles thinking about the energy the velocities the you know energy of all the microscopic particles let's say microscopic that's the statistical thermodynamics this class will be classical thermodynamics we're not going to get into the chemistry the molecules the particles we're going to be looking at the fluid as a whole our class is based on these four laws of thermodynamics all right so we start with zero flow I don't start with the zeroth law well I think that they had lost 1 2 & 3 but then they decided we before we get to the house 1 2 & 3 we need this law we'll call it the zeroth law that says if two bodies are in thermal equilibrium with a third body then they will both have the same temperature I don't know why they needed to define that as a law they did what it just means is that if the temperature of fluid a is equal to the temperature of fluid let's call it C and if B is also equal to the fluid the temperature of fluid C then the temperature of a would be equal to the temperature of B makes perfect sense a little bit obvious that is the zeroth law two bodies are in thermal equilibrium with a third then those two had have the same equilibrium so we can kind of take a third to measure things and if two things are equal to the third then those two things are equal to each other okay first law is conservation of energy this is where we're going to sit almost the whole semester conservation of energy keeping track of if we keep track of all the energy energy can't be created or destroyed it has to go in or out it has to go somewhere and so here is the first law the sum of all the energy in so Sigma means some of all the energy that goes into our system minus the sum of all the energy that goes out alright so for keeping track of everything that's going in keep track of everything that's going out like our bank account balance right then that we will - the change in energy we'd say Delta e change in energy I'd probably leave it as Delta e or we could say energy final minus energy initial or energy to minus energy one let's write this in words the sum of all the work heat energy in minus the sum of all of that work energy heat out would be equal to the change in energy so this is the final energy minus the initial energy so for keeping track of hey it started right here and then an hour later it ended right here then our ending energy minus our starting energy box said I mean we are going to see that again and again that is what I want you to learn from this class conservation region how to calculate and keep track of all the energy going and energy going out and the change in energy in our system and like we said the fill up the last page there's lots of different types of energy that we're going to have to keep track of the second law is is tough a little more abstract talking about entropy and it says the entropy or the measure of disorder of the universe is always increasing so it's just saying that naturally things become less organized things less organized I mean is that not true in in this house in my house I've got three kids and naturally things are gonna get less and less organized unless we put work into it though but if we leave it to be this house is going to get less or nice if you leave it you know if you don't keep take care of things right things become less organized it's kind of a measure of disorder things become more disordered someone's a measure of chaos if we don't put work into things things become more chaotic this gives a direction for some processes if we could measure the disorder if we can measure the entropy we know that total naturally the total entropy is going to increase now we might have pockets where the entropy decreases pockets where the entropy decreases but on on a whole if we look at the universe or something that we could define as the universe entropy is always increasing one of my favorite quotes let's see if I can remember off my head is without hard work nothing grows but weeds that is a little bit about entropy if we leave things to be weeds are gonna grow okay and on a hole entropy is always increasing okay the third law is that as temperature approaches zero Kelvin or zero Rankine Rankine would be the English absolute value temperature scale entropy approaches zero okay we won't deal with those very much first law is where we're spending the most of our time for this class this is the foundation for thermodynamics these four laws of thermodynamics