Temperatuur en thermisch evenwicht

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.