[Music] what s thermodynamics thermodynamics is a science of energy transfer and the effect of the transfer on the physical properties of substances it is based upon the observations of common experiences which have been formulated into laws the applications of thermodynamic laws are found in all fees including but not limited to power plant internal combustion engines refrigerators air conditioners and fuel cells all of these devices make use of heat to achieve useful work and vice-versa a thermodynamic system is defined as a region of space upon which attention is focused the system is separated from the surroundings by a boundary which classifies the system into first closed system where only energy transfer takes place second open system where both energy and mass transfer takes place third isolated system where no transfer takes place most thermodynamic systems are open systems by analyzing such systems attention is focused on a certain volume within the system known as the control volume the surface bounding this open system is called a control surface every system has certain characteristics by which its physical condition may be described example volume temperature pressure etc such characteristics are called the properties of the system when all the properties of the system have definite values the system is said to exist in a different state properties other colonists to describe the state of a system any operation in which one or more properties of a system change is called a change of state when the path during a change of state is completely specified the change of state is called a process for example a constant pressure process a cycle is defined as a series of state changes such that the final state is identical with initial state now we all know that matter is made up of molecules and in turn of atoms for example one millimeter cube of air at standard temperature and pressure that the is 10 to the power 16 molecules each of which has a position and velocity and these positions and velocities are generally not useful for determining how macroscopic systems will act hence we neglect the fact that real matter is made up of and rather take it to be made up of continuous descriptions matter where the properties of matter are cancer as continuous function of space variables like volume pressure and temperature this is the concept of content thermodynamic equilibrium is said to exist in a state when no change in any macroscopic property is seen when the system is isolated from its surroundings there are three types of equilibrium that must be satisfied in order for the system to be in thermodynamic equilibrium first mechanical equilibrium which translates to the absence of Indian balanced force within the system and also between the system and its surroundings second chemical equilibrium which requires no chemical reaction or matter transfer from one part of the system to another and last thermal equilibrium which requires no spontaneous change in the property of the system if it is separated from the surroundings when a body a is in thermal equilibrium with a body B and also separately with a body C then B and C will be in thermal equilibrium with each other this is a zeroth law of thermodynamics it is the basis of temperature measurements which is a distinct property of a thermodynamic system which is measured using a thermometer selecting a reference body taking an talk on the property that changes with temperature a common example is a mercury in glass thermometer which uses length to indicate temperature a closed system and its surroundings can interact in two ways first by work transfer and second my heat transfer both of which are boundary phenomena heat and work are not properties of the system and hence cannot be stored by it they are both path functions that is the magnitude of heat above transfer depends upon the path that system follows during the change of state heat transfer is energy transfer due to temperature difference only all other energy transfers can be charmed as well transfer the first law of thermodynamics is essentially the law of conservation of energy but since we need it in the terms of thermodynamics it can be expressed under two forms a first law for a closed system undergoing a cycle wherein the cyclic integral of the work done is always proportional to the cyclic integral of the heat transferred the constant of proportionality is called the joules equivalent be first law for a closed system undergoing a change of state when heat of work is done on the system resulting in change of state the net energy transfer is stored in the system this energy termed as internal energy is the difference between the work done and the heat rejected by the system the major application of the first law of thermodynamics is to analyze the flow of mass across an open system which is done with a classic steady flow energy equation here comes the end of quick revision of what thermodynamics is finally it's time for this episode's question what is a quasi-static process also it's time to answer last episode's question how are gas tubes shaped molten glass is wrapped around a rotating hollow cylindrical mindil and is drawn by a set of rolls is blown through the mandrel to prevent the glass from collapsing so like subscribe and comment with your feedback to help us make better videos thanks for watching in the next episode of mechanical engineering insiders find out what's the second law of thermodynamics is