 Welcome back. Now we are in a position to exercise ourselves in thermodynamics. We will soon give you a set of exercises, the exercise set A and you will be able to solve this. But before you do any exercises in thermodynamics, there are some preliminary ideas and preliminary issues that one should be aware of and that is we should be conscious of the formal method of solution of problems in thermodynamics. We should know how to solve that. There is a procedure or a formalism involved in it. First thing we have to do is read the specification and I have underlined the word read indicating that what we want is not just reading, we want to read, appreciate and understand what is the problem specification is all about. Then as we read and as we proceed with the solution, we will sketch diagrams, diagrams of the system or systems involved and the processes that the system or systems execute. Sometimes the specification will be quite often will not be complete. So we should read things or appreciate things which are not specified. We can say we should be able to read in between lines or in between words and because of this, we will have to make appropriate assumptions to take care of things which are not specified. As good engineers these assumptions we will need to justify or if some data is available, we may even be able to check the validity of these assumptions. Now when we come to numericals, we must treat with respect the numbers and the dimensions and units of the quantities associated with those numbers. Now the moment we come to units, we will have to combine numbers of different units, so we will have to handle conversion factors properly. And once we obtain the final answer, the exercise is not over. Quite often we will need to comment on the answers because the purpose of solving a problem, doing an exercise is not just doing it, it is to demonstrate that we have learned something. In the next slot, we will be looking at an illustrative example where we will be going through this process. Thank you.