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AP Physics 2: Algebra-Based Practice Quiz: Thermal Energy Transfer and Equilibrium

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 11 questions to check your progress.

Question 1 of 11

A block of copper at 90°C is placed in thermal contact with a block of aluminum at 30°C. In which direction will energy be transferred spontaneously?

All Questions (11)

A block of copper at 90°C is placed in thermal contact with a block of aluminum at 30°C. In which direction will energy be transferred spontaneously?

A) From the aluminum block to the copper block.

B) From the copper block to the aluminum block.

C) No energy will be transferred because the materials are different.

D) Energy will be transferred equally in both directions from the start.

Correct Answer: B

According to the provided content, energy is transferred spontaneously from a higher-temperature system (the 90°C copper block) to a lower-temperature system (the 30°C aluminum block).

What is the fundamental condition required for a net transfer of energy to occur between two systems in thermal contact?

A) The systems must have equal mass.

B) The systems must be in a vacuum.

C) The systems must be made of the same substance.

D) The systems must have a temperature difference.

Correct Answer: D

The provided text states that the transfer of energy between two systems in thermal contact is due to temperature differences between those two systems.

When two systems in thermal contact reach a state where there is no net transfer of energy between them, they are said to have reached:

A) absolute zero.

B) thermal equilibrium.

C) a state of thermal insulation.

D) maximum entropy.

Correct Answer: B

The content defines thermal equilibrium as the state that results when no net energy is transferred by thermal processes between two systems in thermal contact with each other.

Which of the following correctly lists the three thermal processes by which energy can be transferred between systems at different temperatures?

A) Friction, tension, and compression

B) Conduction, convection, and radiation

C) Reflection, refraction, and diffraction

D) Evaporation, condensation, and sublimation

Correct Answer: B

The content explicitly states that the thermal processes by which energy may be transferred are conduction, convection, and radiation.

The term "thermal contact" implies that two systems:

A) are at the exact same temperature.

B) are physically welded together.

C) are able to transfer energy through thermal processes.

D) are perfectly isolated from one another.

Correct Answer: C

The definition provided is: 'Two systems are in thermal contact if the systems may transfer energy by thermal processes.' This means the potential for transfer exists.

At the point of thermal equilibrium, which statement about energy transfer is most accurate?

A) All transfer of energy between the systems ceases entirely.

B) The rate of energy transfer from the hotter system to the colder one is zero.

C) The net transfer of energy between the two systems is zero.

D) Energy transfer reverses, flowing from the colder to the hotter system.

Correct Answer: C

The key concept in the definition of thermal equilibrium is that the *net* energy transfer is zero. Energy may still be exchanged at a microscopic level, but the rates of transfer in both directions are equal, resulting in no net change.

A student places a warm metal block (System A) on a cool plastic block (System B). They are in thermal contact. Which statement best describes the process that follows?

A) Energy will transfer from B to A until both are at the initial temperature of B.

B) No energy will transfer because metal and plastic have different thermal properties.

C) Energy will transfer spontaneously from A to B until thermal equilibrium is reached.

D) The systems will reach thermal equilibrium instantly with no energy being transferred.

Correct Answer: C

This scenario combines two principles from the text: energy is transferred spontaneously from a higher-temperature system (A) to a lower-temperature system (B), and this process continues until thermal equilibrium is reached (no net energy transfer).

All of the following are primary thermal processes for energy transfer EXCEPT:

A) Conduction

B) Convection

C) Oscillation

D) Radiation

Correct Answer: C

The provided content identifies conduction, convection, and radiation as the thermal processes for energy transfer. Oscillation is a type of motion but not a distinct category of thermal energy transfer.

If an observer notes that two systems in thermal contact are not exchanging any net energy, what can be concluded about the systems?

A) One system contains significantly more energy than the other.

B) The systems have achieved thermal equilibrium.

C) The systems are made of materials that cannot conduct heat.

D) A chemical reaction has occurred between the systems.

Correct Answer: B

This question applies the definition of thermal equilibrium in reverse. The condition of 'no net energy transfer' is the definition of thermal equilibrium.

The spontaneous nature of thermal energy transfer implies that the process:

A) occurs from a lower-temperature system to a higher-temperature system without external work.

B) occurs from a higher-temperature system to a lower-temperature system without external work.

C) requires a catalyst to begin.

D) only happens between systems of the same phase (e.g., solid to solid).

Correct Answer: B

The content states that 'Energy is transferred through thermal processes spontaneously from a higher-temperature system to a lower-temperature system.' The term 'spontaneously' implies it happens naturally without external intervention.

Two isolated systems, System 1 (1 kg at 100°C) and System 2 (5 kg at 20°C), are brought into thermal contact. The systems are allowed to interact until a final state is reached. Which of the following statements provides the most complete and accurate description of this final state?

A) System 1 and System 2 will both be at 20°C because System 2 has more mass.

B) System 1 and System 2 will be in thermal equilibrium, meaning there is no longer a net transfer of energy between them.

C) System 1 will have transferred all of its thermal energy to System 2.

D) Energy will have been transferred from System 2 to System 1 because of the mass difference.

Correct Answer: B

Regardless of mass or material, the fundamental process is the transfer of energy from the higher-temperature system (1) to the lower-temperature system (2). This net transfer continues until the systems reach a common intermediate temperature, at which point they are in thermal equilibrium, and the net transfer of energy becomes zero. The other options make incorrect assumptions about the final temperature or direction of energy flow.