 Sanjay Murt, Assistant Professor, Mechanical Engineering Department of Walsh and Instoaptic Knowledge, Slapu. Today, I am going to explain the fifth video of thermodynamics. That is why I am numbering 1, 2, 3, 4, 5, because these are the introduction parts related to the thermodynamics. The learning outcome of this video is student will able to know what is the first law of thermodynamics and second law of thermodynamics, which you can use regularly. Now, when you says that first law of thermodynamics, what is the first law of thermodynamics? There is a law of conservation of energy. So, one form of energy converted to the other form of energy. There is a simple statement. So, this is to be what you call that experiment is be done on this related to the first law of thermodynamics by Jules experiment. What is that Jules experiment? Well, Jules experiment in that a closed content is that vessel is to be there. That vessel is isolated, that is adiabatic vessel, there is no transaction of any heat from system. So, here again, system is the system and it is surrounding, there is no transaction of heat or energy from that system. It is totally adiabatic vessel. There is one thermometer is placed to measure to note down the temperature. Here, one stirrer is to be placed through the pulley arrangement is there, cord and pulley arrangement and the weight is attached on the other side. So, what is the first law of thermodynamics says that one form of energy is converted to the other form of energy. What is the first law of the first law say that Q is equal to U plus W. What is the Q amount of heat that is in Jules, then U that is the capital U that is the internal age of system and W is the work. Now, how the first law of thermodynamics works? Here the vessel is to be there completely isolated thermometer is there, stirrer is there and weight is attached to other side. The known quantity of water is mass is known M1. So, its pressure P1 volume V1 temperature T1 mass M1 is to be there and the stirrer is to be there. On the other end of that stirrer cord is attached to pulley arrangement weight is to be there. So, it is a weight M1 and it is a height at H1 from the base one from the datum one. Where that vessel is to be placed and the weight is some higher side. So, values initial values are P1 V1 T1 M1 U1 H1 kinetic energy Ke1 potential energy. So, all these values are the initial one. Now the weight is allowed to move from height 1 to the height 2. Due to the gravity force it moves from level 1 to the level 2. When the cord is moving downward conditions due to that gravity force due to that pulley arrangement that stirrer get rotated here. When the stirrer get rotated here the temperature of the water is to be increased. When the temperature of water is increased that is to be noted in the thermometer that is T1 to the T2. So that is to be noted. Again mass is same, pressure is same, volume is same but only there is rise in the temperature and so here the loss of what we call as potential energy, MgH1 to the MgH2. Due to which that is to be converted to the rotational mechanical energy. So loss of height that is a, there is a change in potential energy that change in potential to the kinetic rotational mechanical energy. This kinetic rotational mechanical energy can be rise in the temperature of the water that is to be noted. So, here the loss of height, the loss of potential energy is convert to the rise in the temperature. What is the first law says that, first law says that Q is directly proportional to the work done. But before that you says that Q is equal to U plus W, but here you says that the change in internet system they are negligible one, other values like kinetic energy, potential energy, environmental energy, rotational energy, mechanical energy, they have to be only noted that measurable one that is the kinetic energy and potential energy, that is to be, but these are again that the change are minute one, that is why it says that whatever the quantity of rise in the temperature that is related to the this step of work is to be done. So, that is rise in the temperature Q that is the difference is related to the change in the height and due to the gravity force of that system. That is the first law of thermodynamics, but when you know this first law of thermodynamics you go for in a reverse way. Suppose that this weight at now that final stage is that is at a datum level that is at the ground level. Now you can lift from H to level 2 to the level 1 at initial condition, then the stirrer is rotated in a reverse direction. Previously it moves from level 1 to the level 2 it is suppose it is moving in a clockwise direction, there is rise in the temperature that is a T 1 minus T 2 or T 2 minus T 1. Now the weight is artificially lifted from level 2 to the level 1 it comes to initial condition then stirrer rotate in anti-clockwise direction then is that much quantity of heat is to be absorbed that is not happened because it is it moves in only one directions. So, this is the limitations of the first law of thermodynamics that is to be explained in following way. Suppose a cup of hot water hot tea kept in environment its temperature is T 1 that cup when it is placed in a open environment after certain period of time the heat is transmitted from system to the surrounding whether it is going in a reverse way that is not happened. Suppose second example is heating of room in a electric heater the coil is to be circulated in your room the heater it increase the temperature of that water, but when you go for a in a reverse way suppose the heater is supplied you produce the electrical energy that is not happened the paddle work is to be there by paddle work suppose electric motor is to be there due to that motor you go you can rotate that shaft when the shaft is rotated you get some 1000 revolutions example 1000 revolutions per minute and the motor is to be rotated in one minute, but that shaft is rotated in a reverse directions whether to what you call regain that mechanical energy regain the supply energy that is not happened. Suppose the water is moving from the dam from a higher side to the level level and that water is to be injected on the turbine blades the turbine blades rotate you produce the electrical energy, but instead of that turbine blade is rotated in a reverse manner whether that water is moving automatically from lower side to the higher side you regain the potential energy from kinetic energy potential energy that is not happened. So, these are some limitations of the first law of thronage. So, the first law of thronage is related that it is moving only in one directions now it is not a reversible process it is a irreversible process to be there. So, now you says that work is done in a closed system that concept is to be there the piston cylinder arrangement is it is a piston is there and is a cylinder is there in that cylinder gas is to be placed in cylinder the gas condenser. So, when you apply a pressure on that the volume is reduced from level 1 to the level 2 means volume moving from V 1 to the V 2. So, change in the volume that is a change in d V to the limit 1 to 2. So, work done is equal to pressure remain the same that is the pressure that is the weight of that piston or whatever the pressure that is remains constant, but the change in volume from level 1 to the level 2 volume 1 to the volume 2. So, work done W P d V is equal to work done W P into bracket V 2 minus V 1 of the closed system. So, when you know the first law of thermodynamics, now you go for a second law of thermodynamics. What is the second law? In the second law there are two statements are the Kelvin Planck statement and cross state statement. So, one of the statement is the Kelvin Planck statement. In the Kelvin Planck statement here the source is the temperature T 1 the higher side temperature is to be there it is a sink T 2 low temperature body is to be there in between heat engine is to be placed. Here it is heat engine when heat is in natural condition heat convection by convection heat is moving from higher side to the lower side. So, when it is moving from higher side to the lower side you get the work from that system Q 1 plus T 2 work done W is equal to Q 1 plus T 2, but this work in which to be that is a Kelvin Planck statement it is moving that on the second that is Clausius statement here again it moves from higher side to the source to the sink higher should be the low side it is completely consumed by that heat pump that is not happen. So, when you go for the first law of thermodynamics second law of thermodynamics they have to be moving in only one direction systems are to be there. So, these are the statements that that is a heat pump and heat engine heat pump is heat pumping is going on that is heat is moving from without what you call consumer work or heat is moving from lower side to the higher side here it moves from lower side to the higher side you have to required some work is to be there due to that work heat is moving from lower side to the higher side and pumping action is going on and heat engine is to be there you get the heat from that system that is higher side to the lower side, but you have to require some external source of energy. So, when you know the first law of thermodynamics when you know the limitations of the first law whether you go some example for this limitations of the first law of thermodynamics which can regularly used it again in your house minimum one bike is to be there the fuel is to be burned when the fuel is to be burned you get a reciprocating motion due to the reciprocating motion you get a rotational mechanical energy you get the rotational mechanical energy the bike is moving from one end to the other end. Suppose the biking moving in one directions from one state to the another state now that bike is moving moving from two to one in a reverse way whether you have to produce the petro not. So, this is the limitations of the first law of thermodynamics simple example is to be there. So, here you know the first law of thermodynamics related to the juice x-men then limitations of the first law then second law of that is heat pump and heat engine Kelvin statement and process statement and reference for this one is basic mechanical engineering by R. S. Kurmeiser. Thank you.