Temperature and thermal equilibrium help explain how we compare how hot or cold objects are and why thermometers can measure the temperature of other things. This lesson introduces the operational meaning of temperature, the conditions for thermal equilibrium, and the zeroth law of thermodynamics.
Our everyday senses tell us that some objects feel hot and others feel cold, but those sensations alone do not provide a precise scientific measurement. Temperature is operationally defined as the quantity measured by a thermometer. This definition connects temperature to an observable measurement.
All flashcards
What is the operational definition of temperature?
Temperature is the quantity measured by a thermometer. Microscopically, it is proportional to the average kinetic energy of the translational motion of particles.
What is heat transfer?
Heat transfer is the movement of energy from one place or material to another as a result of a temperature difference.
What is thermal equilibrium?
Two objects are in thermal equilibrium when there is no net energy transferred between them. They have the same temperature.
What does the zeroth law of thermodynamics state?
If system A is in thermal equilibrium with system B, and B is in thermal equilibrium with system C, then A is in thermal equilibrium with C.
How does a thermometer measure another object's temperature?
A thermometer measures its own temperature. Once it reaches thermal equilibrium with the object, both have the same temperature, so the thermometer's reading indicates the object's temperature.
Quiz questions
How is temperature operationally defined?Answer: The quantity measured by a thermometer.
What condition characterizes thermal equilibrium between two objects?Answer: They have the same temperature and no net energy transfer occurs.
If system A is in thermal equilibrium with B, and B with C, what follows from the zeroth law?Answer: A is in thermal equilibrium with C.
Why can a thermometer's reading indicate an object's temperature?Answer: At thermal equilibrium, the thermometer and object have the same temperature.
Based on University Physics Volume 2 by Samuel J. Ling, William Moebs, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.