Home | | Physics 11th std | Quasi-static process

First law of thermodynamics - Quasi-static process | 11th Physics : Heat and Thermodynamics

Chapter: 11th Physics : Heat and Thermodynamics

Quasi-static process

Consider a system of an ideal gas kept in a cylinder of volume V at pressure P and temperature T.

Quasi-static process

 

Consider a system of an ideal gas kept in a cylinder of volume V at pressure P and temperature T. When the piston attached to the cylinder moves outward the volume of the gas will change. As a result the temperature and pressure will also change because all three variables P,T and V are related by the equation of state PV = NkT. If a block of some mass is kept on the piston, it will suddenly push the piston downward. The pressure near the piston will be larger than other parts of the system. It implies that the gas is in non-equilibrium state. We cannot determine pressure, temperature or internal energy of the system until it reaches another equilibrium state. But if the piston is pushed very slowly such that at every stage it is still in equilibrium with surroundings, we can use the equation of state to calculate the internal energy, pressure or temperature. This kind of process is called quasi-static process.

A quasi-static process is an infinitely slow process in which the system changes its variables (P,V,T) so slowly such that it remains in thermal, mechanical and chemical equilibrium with its surroundings throughout. By this infinite slow variation, the system is always almost close to equilibrium state.

 

EXAMPLE 8.14

Give an example of a quasi-static process. Consider a container of gas with volume V, pressure P and temperature T. If we add sand particles one by one slowly on the top of the piston, the piston will move inward very slowly. This can be taken as almost a quasi-static process. It is shown in the figure


Sand particles added slowly- quasi-static process

 

Tags : First law of thermodynamics , 11th Physics : Heat and Thermodynamics
Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
11th Physics : Heat and Thermodynamics : Quasi-static process | First law of thermodynamics


Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.