AP Physics 2: Algebra-Based Flashcards: Entropy and the Second Law of Thermodynamics
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
What is the second law of thermodynamics?
The second law of thermodynamics states that the total entropy of an isolated system can never decrease and is constant only when all processes are reversible.
Card 1 of 10
All Flashcards (10)
What is the second law of thermodynamics?
The second law of thermodynamics states that the total entropy of an isolated system can never decrease and is constant only when all processes are reversible.
Under what specific condition can the entropy of an isolated system remain constant?
The entropy of an isolated system is constant only when all processes the system undergoes are reversible.
Provide a qualitative description of entropy related to energy distribution.
Entropy can be qualitatively described as the tendency of energy to spread.
How does entropy relate to a system's ability to perform work?
Entropy can be described as the unavailability of some of a system's energy to do work.
Can the entropy of a closed system decrease? Explain why or why not.
Yes, the entropy of a closed system can decrease because energy can be transferred into or out of the system.
Why can a closed system's entropy decrease while an isolated system's cannot?
A closed system can decrease in entropy because it can transfer energy to its surroundings, a process not possible for an isolated system.
Is it possible for the entropy of an isolated system to decrease?
No, according to the second law of thermodynamics, the entropy of an isolated system never decreases.
Contrast the potential for entropy change in an isolated system versus a closed system.
The entropy of an isolated system never decreases, but the entropy of a closed system can decrease through energy transfer.
Define entropy in two qualitative ways.
Entropy can be described as the tendency of energy to spread or as the unavailability of some of a system's energy to do work.
What is the general trend for the change in entropy of an isolated system over time?
The total entropy of an isolated system can never decrease over time; it either increases or remains constant.