Thermal conduction

queuetea · Aug 15, 2012

in winter, wooden floor feels cold to the barefoot but the rugs and carpets don not feel cold although the floor and carpet are at the same temperature?

mfb · Aug 15, 2012

Your feet are warmer than the floor, so heat is transported from your feet to the floor. Wood can do this quicker, therefore it feels colder.

queuetea · Aug 15, 2012

and why for the rugs and carpets do not feel cold although the floor and carpet are at the same temperature?

mfb · Aug 15, 2012

The conductivity is so low that you do not notice the effect. Both have a lot of air (bad conductor) and wool (another bad conductor, especially as it contains more air inside).

queuetea · Aug 15, 2012

okay thank you sir :)

sophiecentaur · Aug 15, 2012

Assume that the temperature of the inside of your foot is always the same and the temperature 'below the floorboards' is also the same. There will be a thermal gradient from your body tissue, across your skin, through any insulation and the floor. If the intermediate layer has low conductivity, the surface of your skin will have a higher temperature (It's not just an illusion) because there will be a greater temperature drop across the insulation layer and the overall rate of heat flow will be lower.

There is a direct analogue here with an electrical potential divider, consisting of a chain of resistors, where the PD is shared across the resistors. Inserting a high value of resistor in series with a resistor will reduce the total current, which will reduce the PD across the original resistor.

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Thermal conduction

queuetea

mfb

Staff: Mentor

queuetea

mfb

Staff: Mentor

queuetea

sophiecentaur

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