---
title: "Thermal Equilibrium — AP Physics 2 Definition & Exam Guide"
description: "Thermal equilibrium is the state where objects reach the same temperature and net heat flow stops. It anchors AP Physics 2 gas law, internal energy, and conduction problems."
canonical: "https://fiveable.me/ap-physics-2-revised/key-terms/thermal-equilibrium"
type: "key-term"
subject: "AP Physics 2"
---

# Thermal Equilibrium — AP Physics 2 Definition & Exam Guide

## Definition

Thermal equilibrium refers to a state where two or more objects are at the same temperature and there is no net flow of heat between them. In this state, thermal energy is evenly distributed among all objects involved.

## Related Study Guides

- [2.10 Thermal Conductivity](/ap-physics-2-revised/unit-2/thermal-conductivity/study-guide/LXcVaVW1YFpFt8nSgYo9)
- [Unit 2 Overview: Thermodynamics](/ap-physics-2-revised/unit-cg091QJ4Pix6hWo9/review/study-guide/MOzJLnCy4BQKR0jeZ2uh)
- [2.2 Pressure, Thermal Equilibrium, and the Ideal Gas Law](/ap-physics-2-revised/unit-2/pressure-thermal-equilibrium-ideal-gas-law/study-guide/QVXmkTBoy51OJkDbxMp7)
- [2.7 Internal Energy and Energy Transfer](/ap-physics-2-revised/unit-2/internal-energy-energy-transfer/study-guide/zXnfwA3wvPwaKNgzTpk0)

## Review

### Related Terms

- [Heat Transfer](/ap-physics-2-revised/key-terms/heat-transfer): The process by which thermal energy moves from one object or system to another due to temperature differences.
- [Conduction](/ap-physics-2-revised/key-terms/conduction): The transfer of heat through direct contact between particles or objects.
- [Convection](/ap-physics-2-revised/key-terms/convection): The transfer of heat through fluid motion caused by temperature differences within that fluid.