AP Physics 2: Algebra-Based Flashcards: Thermal Energy Transfer and Equilibrium
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
What is meant by two systems being in 'thermal contact'?
Two systems are in thermal contact if they are able to transfer energy between each other by thermal processes.
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What is meant by two systems being in 'thermal contact'?
Two systems are in thermal contact if they are able to transfer energy between each other by thermal processes.
What fundamental condition must exist for thermal energy to be transferred between two systems in contact?
A temperature difference must exist between the two systems for thermal energy to be transferred.
What is the consequence when the net energy transfer between two systems in thermal contact is zero?
The consequence is that the systems are in thermal equilibrium with each other.
What term describes the state that results from the spontaneous transfer of energy from a hot system to a cold system?
This process continues until thermal equilibrium results, where no more net energy is transferred between the systems.
What is the relationship between temperature difference and thermal equilibrium?
A temperature difference drives the transfer of energy, and thermal equilibrium is the state achieved when this temperature difference no longer exists.
What are the three thermal processes by which energy can be transferred between systems?
The three thermal processes for energy transfer are conduction, convection, and radiation.
An ice cube is dropped into a glass of warm water. Describe the spontaneous flow of energy.
Energy spontaneously flows from the higher-temperature system (the warm water) to the lower-temperature system (the ice cube).
In which direction does thermal energy spontaneously transfer between two systems?
Energy is transferred spontaneously from a higher-temperature system to a lower-temperature system.
If a hot object is placed in thermal contact with a cold object, when will the net transfer of energy between them stop?
The net transfer of energy will stop when the two objects reach thermal equilibrium, meaning they are at the same temperature.
Define thermal equilibrium.
Thermal equilibrium is the state reached when no net energy is transferred by thermal processes between two systems in thermal contact with each other.
How is the transfer of energy due to temperature differences described?
It is described as the transfer of energy between two systems in thermal contact due to the temperature differences of those two systems.