 myself, Professor S. M. Mutt from Walchand Institute of Technology, Sholapur from Mechanical Engineering Department. Today we deals with the gas processes. The outcomes from this topic is student will able to discuss the various gas processes. Basically there are different type of processes. When gas is heated or heat is to be removed at a different stages. When the constant pressure process is there, constant volume process is there, constant temperature process is there. At that time some transactions are to be going on related to the heat, work, internal energy and enthalpy. So, today first we will deal with one of that processes that is the constant volume processes. Volume is to be constant. So, when volume is to be constant there by the first law of thermodynamics the formula is Q v is equal to change in internal energy plus work done. So, when this is to be going on and when the volume remains constant you take a container. In that container gas is to be filled which pressure volume temperature is to be known at initial stage pressure p 1 volume v 1 temperature d 1 mass m 1 internal energy u 1 enthalpy h 1. Now, heat is to be added for this gas which is to be at a constant volume that is v 1 is equal to v 2. Now, here what your quantity of heat is to be added here in this process for the constant volume gas volume remains constant. When the volume remains constant work done is equal to p into d v or it is equal to p into bracket v 2 minus v 1, but as it is a constant volume process it is equal to 0. So, work done is equal to 0. When the work done is equal to 0 then quantity of heat supplied by the first law of thermodynamics is change in internal energy plus work done, but heat supplied is equal to change in internal energy plus work done work done is equal to 0. Therefore, q heat supplied is equal to change in internal energy. So, when heat supplied is to be there heat supplied is to be it is equal to mass into specific heat into change in the temperature. So, it is equal to mass is m specific heat at constant volume that is c v and change in temperature is equal to t 2 minus t 1. So, heat supplied q is equal to m c v d t and which is to be denoted by kilo joule per kg degree Kelvin. So, for a constant volume process heat is equal to m c v d t change in internal energy is equal to m c v d t as work done is equal to 0. So, these are the values when volume remains constant volume is to be constant. So, this is the first process that is the constant volume process. Now, we are go for the next process pressure remains constant pressure is constant as in the drawing the previous graph pressure is p 1 is equal to p 2 and volume is v 1 and this volume is constant volume is v 2. Again just like previous one whatever the quantity of heat loss here in this case is to be carried out by a part of heat is utilized to do the work and part of heat is utilized to increase its own energy that is called as a internal energy of that system. So, by the first law of throat dynamics q is equal to change in internal energy plus work done, but in this case and the pressure remains constant. Now, take a example of the simple piston cylinder arrangement. So, here weight of that it is a piston cylinder arrangement weight of the piston is act its own weight and that is a load acting on that gas. So, initially when the gas is there its pressure is p 1 volume v 1 temperature is t 1 when you have to add the heat it expands from level 1 to the level 2. When it moves from level 1 to the level 2 here in this case pressure is remains constant p 1 is equal to p 2, but volume is increases from v 2 and temperature is in p of t 2 and pressure is the same one. So, now we have to calculate the value of heat work internal energy just like previous one we have to calculate the heat work and internal value when the constant volume process is to be there, but when q by the first law of throat dynamics q is equal to change in internal energy plus work done. So, the change in value of change in internal energy part of it is whatever the quantity of heat supplied and the constant pressure process part is utilized to do the work that is expansion of that gas. So, the piston is moving from level 1 to the level 2 that much quantity of work is done and remaining is to increase its own energy in different forms of energy that is called as a internal energy that internal is deals with a different forms of energies this internal that is deals with a kinetic energy, potential energy, vibrational energy, rotational energy. So, on the different forms of energies these are the different forms of energies. Now, we have to calculate the internal energy. So, internal energy is equal to again when it is a constant pressure process is there its value is equal to m c v d t is equal to m c v into bracket t 2 minus t 1 that is the value of internal energy. Now, you go for the value of work done work done it moves from level 1 to the level 2 it is equal to p d v or it is equal to p into bracket v 2 minus v 1 that is the value of work done. So, therefore, heat supplied is equal to change in internal energy plus work done you put the values is m c v into bracket t 2 minus t 1 plus p d v. So, therefore, the value of q is equal to m c v into bracket t 2 minus t 1 plus do the work p d v. So, this is the value of heat and work. So, in this session we are dealing with with the calculating the value of heat, work and internal energy when the pressure remains constant and when the volume remains constant we have to calculate the value of work heat work and internal energy of that system. Thank you.