Practice question · Select all that apply
Which of the following are irreversible processes?
Hints
- Ask whether the process could be run backwards leaving no trace.
- Anything dissipating energy as heat cannot be undone.
Show the answer
- A. Friction converting kinetic energy to heat
- C. A gas expanding freely into a vacuum
- D. Heat flowing from hot to cold spontaneously
Why
Free expansion, heat flow, and friction are irreversible (entropy increases). Quasi-static processes are reversible idealizations.
Practise Second Law of Thermodynamics and Entropy
The app has 6 more questions on this lesson, and keeps your place in the course. Physics I is free to start.
More questions on Second Law of Thermodynamics and Entropy
- Order these milestones in the history of entropy and the second law.
- A drop of ink disperses through a glass of water and never spontaneously regathers. Yet each molecular…
- A heat engine runs between a 600 K flame and a 300 K environment. Estimate the maximum possible efficiency,…
- The entropy of an isolated system can spontaneously decrease.
- A Carnot engine takes in 900 J of heat per cycle from a reservoir at Th = 450 K and rejects heat at Tc = 150…
- The second law forbids processes the first law permits. What does it add?