taking readings for temperature

[exequor]

why is it better to take temperature readings for a substance when it is cooling down instead of when it is warming up?

[exequor]

i was wondering could it be because when the substance is heating up the thermocouple would record the temperature of both the temperature of the substance whose temperature you want to find and the temperature of the surroundings but when it is cooling down only the temperature of the substance would be found.

[HallsofIvy]

What reason do you have to think that "while cooling down" is better than "while warming up"?

[exequor]

well the question that i was asked was why was it better to take it when cooling as opposed to when warming up.

[TALewis]

Maybe it has something to do with some hysteresis of the instrument?

[turin]

You could probably get away with posting this in the regular physics forums (i.e. classical mechanics). Incidently, I must appologize that I have no idea for an answer to your question. Hysteresis sounds tenable.

[remcook]

my guess:

if you're heating stuff up with a burner, then heating up goes faster than cooling down. So the thermometer gets more time to adjust.

total guess.