[Zilali]

On a cold day, if you've ever been slapped on the face or had your ears flicked etc etc you'll know it hurts like hell. But why is this? Seeing as cold usually numbs pain, shouldn't it be the opposite?

[InfiniteNow]

Water when slapped will ripple and spread the force. Ice when slapped will absorb the impact locally, or even shatter. My guess would be that it is similar with skin. It is raw, the blood is not flowing to it as well, and it is less flexible and more rigid. The smack also causes capilarries to burst and more blood to flow in, and perhaps part of the "pain" sensation is the influx of blood to the region.

Lots of maybes and perhapses in the above though, so take it with a grain of salt.

[LJP07]

InfiniteNow said:

Lots of maybes and perhapses in the above though, so take it with a grain of salt.

Maybe also when your slapped the heat from someones elses hand could be a stark change from cold, like putting boiling water into really cold water, has a hissing sensation, the hissing is the noise you make when getting slapped, and the heat could contribute to the pain, Infinites Idea seems good.

Did you get slapped recently?

[Zilali]

Prolu2007 said:

Maybe also when your slapped the heat from someones elses hand could be a stark change from cold, like putting boiling water into really cold water, has a hissing sensation, the hissing is the noise you make when getting slapped, and the heat could contribute to the pain, Infinites Idea seems good.

Did you get slapped recently?

But it's the same kind of pain if you say get hit by a snow ball so I wouldn't think it would be anything to do with a heat difference.

and no thankfully I havnt been slapped for a while, I was just thinking back to primary school when you'd go round flicking peoples ears on a cold day, ah the fun we used to have.

ah well maybe its just one of the mysteries of life.

[LJP07]

Zilali said:

But it's the same kind of pain if you say get hit by a snow ball so I wouldn't think it would be anything to do with a heat difference.

If you get hit by a snowball, there is still an initial impact. And that initial impact could create heat, even for a split second enough for you to feel it.
If you got hit by a snowball in the blistering heat ( even though snow wouldn't be around in those conditions ), you wouldn't feel it as much, so cold hitting cold or heat hitting cold could call for the worst degree of pain, a hot hand hitting a hot face wouldn't be that sore.

[Turtle]

Zilali said:

On a cold day, if you've ever been slapped on the face or had your ears flicked etc etc you'll know it hurts like hell. But why is this? Seeing as cold usually numbs pain, shouldn't it be the opposite?

According to this source, it because the nerves go from sending cold messages, to sending cold and pain messages.
http://www.durhamreg...brary/kids/cold

[Zilali]

Interesting thanks, cheers for all the replies.