Thermodynamics begins by identifying the part of the universe being studied and describing its state. This lesson introduces systems, surroundings, thermodynamic variables, and the distinction between quasi-static and non-quasi-static processes.
A system is the part of the universe whose properties are of interest. Everything outside the system that can interact with it is called the surroundings. A system could be a single atom, a gas in a cylinder, or even the entire Earth.
All flashcards
What is a quasi-static process?
An idealized change slow enough that the system remains arbitrarily close to thermodynamic equilibrium throughout.
What is the first law using work done by the system as positive?
ΔEint=Q−W, where Q is heat entering the system and W is work done by it.
What happens to an ideal gas's internal energy in an isothermal process?
It remains unchanged because an ideal gas's internal energy depends only on temperature.
How does adiabatic expansion affect a gas?
The gas does work, reducing its internal energy and generally lowering its temperature.
How are reversible and quasi-static processes related?
Every reversible process is quasi-static, but a quasi-static process can be irreversible if dissipation occurs.
Quiz questions
With work done by the system taken as positive, which equation expresses the first law?Answer: ΔEint=Q−W
For a quasi-static process at constant pressure, what is the work done by the system?Answer: W=pΔV
What is the boundary work during a constant-volume process?Answer: It is zero because the system's volume does not change.
What role does an ideal heat bath play in an isothermal process?Answer: It supplies or absorbs heat while maintaining its temperature.
Which statement correctly relates reversible and quasi-static processes?Answer: A reversible process is quasi-static, but a quasi-static process may be irreversible.
Based on University Physics Volume 2 by Samuel J. Ling, William Moebs, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.