Naked Science Forum
General Science => General Science => Topic started by: paul.fr on 11/05/2007 22:18:23
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Two identical houses. one has a tiled/wooden floor, the other has carpets. They are both heated to a pleasent 20 degrees, so why does the house that is carpeted not only feel warmer generally, but your feet feel noticeably warmer. why?
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Carpet is a good insulator of heat. Wood is a bad insulator of heat. Am I right?
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More to the point - carpet traps a lot of air, and air is a good insulator (bearing in mind that 20C is still cold in comparison to the 36C that your body is trying to maintain).
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Yes.. Which is why, when we are cold, our hairs ***** up, to trap a lot of air. [;D]
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Yes.. Which is why, when we are cold, our hairs ***** up, to trap a lot of air. [;D]
The hairs on your skin, or the sheep's hairs on the floor - not much difference - it is all hair of one kind or another (except maybe the sheep do it better).
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Your feet feel warmer with carpet because tile and wood are better conductors of heat than carpet. Remember that although you talk about a pleasent 20 degrees this is still significantly lower than your core body temperature - so whether or not you feel cold simply indicates how fast you are losing heat to your surroundings. It's the rate of heat loss that's important. This is why it's possible to get very cold very quickly even in a relatively warm bath; and why windier days feel colder than a still day with the same air temprature.
Your feet are reasonably good insulators - one of the reasons why it is possible to walk on hot coals - but prolonged contact with a surface (e.g. a floor) will result in a significant loss of heat. If you're looking for a really 'cold' floor try metal; for a 'warm one try polystyrene?
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Your feet are reasonably good insulators - one of the reasons why it is possible to walk on hot coals
The issue about walking on hot coals is much debated, but at least one explanation I had heard was down to the Leidenfrost effect.