In our everyday lives we often use the words hot and cold when we talk about temperature
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
In our everyday lives we often use the words *hot* and *cold* when we talk about *temperature*. In our exploration of these terms, we will ask some thought-provoking questions.
(a) How can we know when something is hot or cold?
(b) When we use the terms hot and cold, are they *absolute*, or are they *relative* to something else?
(c) Is it reasonable to describe temperature as a measure of hotness, or coldness?
(d) When we touch a hot object, how does a physicist explain the sensation of it being hot?
(e) How does a physicist explain the sensation of something feeling cold?
(f) How is it possible for a person to touch an object and make a reasonable estimate of its temperature? Give an example to illustrate your answer.
(g) If you touch steam at a temperature of 100 °C and an equal mass of water at the same temperature, do they feel the same? If not, why do they feel different?
(h) Does your answer to part g suggest that our sense of touch is sometimes wrong? Should we be concerned?
(i) How does a physicist explain what is happening when we touch something that is hot or cold?
(j) Is it reasonable, therefore, to consider that a difference in temperature causes a net flow of energy—in a similar way to a difference in electrical potential causing an electrical current?
(k) So, how would a physicist describe that two objects in thermal contact with each other are at the same temperature?