18.1:
Temperature and Thermal Equilibrium
Temperature is the measure of hotness or coldness of a body, and it can be recorded with a thermometer.
The hotter body has a higher temperature, whereas the colder one has a lower temperature.
For example, boiling water feels hot as it has a higher temperature than cold water.
If hot and cold water are mixed, heat will transfer from the hot to the cold water until their temperature becomes equal.
After attaining a uniform temperature, the heat transfer will stop, and the water is said to be in thermal equilibrium.
If the warmed water is placed inside a refrigerator, it will cool down until it reaches the refrigerator's temperature.
Thus, thermal equilibrium is the condition when there is no further heat transfer between two connected systems.
If one body is separated from the other system by some insulator, it will delay the process of thermal equilibrium.
Therefore, a thermal flask can keep coffee hot for long, as the vacuum present between the walls of the flask acts as an insulator and restricts heat transfer.
18.1:
Temperature and Thermal Equilibrium
Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as thermodynamics. It is not always easy to distinguish heat and temperature.
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is proportional to the average translational kinetic energy, which provides a more physical definition. Differences in temperature maintain the transfer of heat throughout the universe. Heat transfer is the movement of energy from one place or material to another as a result of a difference in temperature. The transfer of heat can change the temperature, and it will affect everything from the behavior of atoms and molecules, to cooking, to the weather on Earth, and to the life cycles of stars. One can feel heat entering the body from the summer Sun or from hot coffee or tea after a winter stroll. One can also feel heat leaving the body from the chill of the night or the cooling effect of sweat after exercise.
Suggested Reading
- OpenStax. (2019). University Physics Vol. 2. [Web version]. Retrieved from https://openstax.org/books/university-physics-volume-2/pages/1-1-temperature-and-thermal-equilibrium.