Which takes longer, to cool down or to warm up?

[Casanova]

i'm sure it's quicker to freeze than to boil. Especially with flash freezing (a phenomenon where water get's to down to -21c and then when you disturb the water it instantly freezes in front of your eyes).

If room temperature is 21ºC; and you have two cups of water - one at 0ºC (frozen) and one at 42ºC (equidistant from room temperate);

The cup that is at 42ºC will cool down faster than the cup at 0º for various reasons. Namely, the frozen water has no convection as it is a solid, it also has to change state from a solid to a liquid which requires a higher energy curve.

---------- Post added 26-10-2010 at 04:48 AM ----------

i'm sure it's quicker to freeze than to boil. Especially with flash freezing (a phenomenon where water get's to down to -21c and then when you disturb the water it instantly freezes in front of your eyes).

temperature change required to boil water from room temperature - 79º
temperature change required to freeze water from room temperature - -21º

it seems fairly likely that its easier to freeze.

but a more obvious factor - if its a really hot substance heating up the water (kettle) and a not-very-cold setting cooling it down, like only -1º, it'll heat up a lot faster.

there are so many variables to this question it cant even be considered.

[Richie]

to warm up.. trying to cool down is so much harder because if your brains saying your hot your still gonna sweat like mad. Just flick on the radiators and throw a blanket over you.