 Within thermodynamic analysis we will also be looking at properties and we'll be using properties extensively throughout the course so let's take a look at the different types of properties that we will be dealing with. When we're discussing properties we have two different types there are what are referred to as being extensive properties and these are essentially properties that are dependent upon the mass or the size of the system. Examples of these could be mass itself so mass or volume or total energy and notice with the exception of mass what I'm doing for the extensive properties is I'm writing them as being a capital letter so in the case of volume a capital V total energy a capital E. We'll talk about specific properties in a moment but before we get to that we also have intensive properties and these are properties that do not depend upon the size of the system and examples of these could be temperature or pressure so temperature and we will use the nomenclature capital T for temperature and capital P for pressure. Now I had mentioned that we have extensive properties we have intensive properties we also have specific properties. What specific properties are is they are basically just extensive properties per unit mass and so examples of these specific volume and here we use a little v don't confuse it with velocity in thermodynamics this little v is actually the specific volume and that is defined as being the volume divided by the mass of whatever system we're looking at or size of volume. We have specific total energy and here that is little e which is the total energy expressed as a capital E divided by mass and a final example is specific internal energy. Remember we looked at internal energy when we were discussing the first law and here we use a little u all of our specific properties will be little letters so little u and then the extensive property would be capital U for internal energy divided by the mass and so those are specific properties that we will be using for a lot of our analysis. So we use properties to describe the state or the the system itself so a system is described by its properties. Another thing we can say is that these are macroscopic values that are assigned without knowledge of the history of the system so they're macroscopic characteristics so properties are assigned and we use them to describe the state of the system which we will talk about in a little more detail in a few moments. Where do properties come from? Properties come from a number of different sources so the origins of properties include we can have properties that we directly measure examples of these could be pressure and temperature you have a pressure transducer you have a thermometer so you're measuring properties directly so they can be directly measurable. Second place where we can get properties is they can be defined by the laws of thermodynamics an example of that is entropy which we will look at later on in this course or they can be defined by mathematical combinations of other properties and an example of that is enthalpy which consists of internal energy plus pressure times the specific volume but we will look at that later. So those are properties and they are very important within thermodynamic analysis because they are what we are using to do a lot of our analysis. We're looking at describing the state of a system within analysis and and we use the properties to do that and then we also use the properties to calculate different aspects within the system so the next thing that we're going to look at is we're going to look at states and processes.