Welcome dear students welcome to the chapter thermodynamics in this chapter we start with knowing the basic terminologies in this module because understanding these basic terminologies we can understand the chapter better ok let’s see what is the basic terminologies that we are going to studied in this module very very basic terms involved in this chapter first of all what do you mean by thermodynamics , thermodynamics is a branch of physics which deals basically with the conversion of heat energy into mechanical work or mechanical work into heat energy so it is the branch of physics which deals with a transfer energy from one place to another and conversion of heat energy into mechanical work or vice versa that is thermodynamics for me. Let’s see a simple example I got a cylinder me with me which is fitted with piston you can see on the screen and which has ideal gas in it. I supply heat energy how much I supply heat energy dQ amount of heat energy has been supplied and this energy what it does please observe that then you understand the meaning of thermodynamics this dQ supplied increases the volume of gas that is implies pushing the piston upward so dW amount of work is done how much work will be done dW amount of work is done so heat energy supply is converted into work and that is what is thermodynamics all about yeah let’s try to understand different types of system . what do you mean by thermodynamic system surrounding all that thermodynamic system is the quantity of matter certain quantity of matter having fixed identity and mass let’s see what is that A certain quantity of matter part of the matter having fixed identity and mass we call it thermodynamic system example, don’t think big about thermodynamic system is little water you’re got going to boil that and then that water becomes a system for you maybe I have gas in a cylinder that is a system for me look at this example water in a beaker may be 50 cc water Is that it is a system for you , you are expecting that , yes look at that In a container I’ve got gas that is a system for me having fixed identity and mass let’s see what is surrounding you must understand that anything other than the system in this universe become surrounding matter outside the system that becomes surroundings . so you have to understand that thermodynamic system continuously interacts the matter outside the system and that matter outside the system we are calling it as surrounding look at that delicious coffee may be a tea is presented in the cup that is the system for me now this system is a tea or coffee remember it interacts something outside matter outside and that part which is outside the system we are calling it as surrounding we go into different types of system right now what do you mean by open system , open system involves exchange of heat energy and matter between system and surrounding that system I m calling it as open system if there is exchange of heat and matter takes place between system and surrounding call that system as open system look at this piston and cylinder you can see in the picture which has gas in it and you supply the heat energy when you supply heat energy you can see that the gas expands work has been done yes excess heat energy is there what happened to the excess heat energy that will got . so it has got exchange of heat energy as well as matter and that system we are calling it is the open system lets go to the closed system means what a system in which you have got only action exchange of heat but not matter that is absolutely no matter exchange yes, if the exchange is only heat energy not the matter between the system and surrounding we call it as a closed system. cylinder provide with the piston having the ideal gas you supply heat energy remember only the heat energy exchange between the system and surrounding not the matter you can seen that work has been done but there is no matter to exchange let’s see what is that work done dW amount of work done but no amount of matter exchanged between system and surrounding yes will know it isolated system no exchange of heat and matter between the system and surroundings let’s see that example no exchange of matter and heat between the system and surroundings look at this thermally isolated system nothing is going to inside neither heat not the matter the system is called as isolated system non conducting wall … thank you.