Reversible isothermal compression of the gas at the "cold" temperature, T 2. The gas expansion causes it to cool to the "cold" temperature, T 2.
![describe the second law of thermodynamics describe the second law of thermodynamics](https://image.slidesharecdn.com/etd-150215235610-conversion-gate02/95/second-law-of-thermodynamic-4-638.jpg)
The gas continues to expand, doing work on the surroundings, and losing an equivalent amount of internal energy. Isentropic (reversible adiabatic) expansion of the gas (isentropic work output). For this step (2 to 3 on Figure 1, B to C in Figure 2) the mechanisms of the engine are assumed to be thermally insulated, thus they neither gain nor lose heat. ɧ =$\left( $ from the high temperature reservoir.Ģ. While, according to the first law, matter and energy must remain constant in quantity, the quality of. The second law states that entropy never decreases entropy can only increase. The first law states that matter and energy cannot be created, nor can they be destroyed. If Q 1 is the amount of heat absorbed from the source and Q 2 be the heat rejected to the sink, then the efficiency of the heat is given as The first and second laws of thermodynamics relate to energy and matter. Isolated systems spontaneously evolve towards thermodynamic equilibrium, the state with maximum entropy. This engine consists of a cylinder fitted with the piston.Ī heat engine with 100% efficiency is only a theoretical possibility. The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible. The petrol engine was developed by Otto in 1877 and hence it is also called Otto engine. What is petrol engine? Draw its PV diagram. The second law of thermodynamics implies that equilibrium corresponds to the maximum total entropy, and that a system prepared in a nonequilibrium macrostate. We use petrol engines for vehicles like cars, airplanes, scooter, etc and diesel engines for vehicles like cars, bus, truck, scooter, etc. Where do we use petrol and diesel engines? (iii) In reversible process, the sum of entropies of system and surrounding remains constant but in an irreversible the total entropy of the system and surrounding increases. (a) Describe how the Second Law of Thermodynamics works for the following situation: A 900-meter high waterfall falls directly onto a rocky surface at the bottom. (ii) The net entropy of the universe in any natural process always increases and tends to acquire maximum value. (i) All spontaneous process is irreversible in nature. The second law also states that the changes in the entropy in the universe can never be negative.įollowing are the statements of second law of thermodynamics:
![describe the second law of thermodynamics describe the second law of thermodynamics](https://i.ytimg.com/vi/I13cQ4tgcUc/maxresdefault.jpg)
The Second Law of Thermodynamics states that the state of entropy of the entire universe, as an isolated system, will always increase over time.