# Grrrrrrr heat problems

1. Feb 23, 2004

### moonlit

I have two problems that I can't figure out:

1) A skier wears a jacket filled with goose down that is 15.5 mm thick. Another skier wears a wool sweater that is 7.13 mm thick. Both have the same surface area. Assuming the temperature difference between the inner and outer surfaces of each garment is the same, calculate the ratio of heat lost through wool to heat lost through goose down during the same time interval.

I know wool=0.040 and goose down=0.025 but how do I go about getting the ratio?

2) The amount of heat per second conducted from the blood capillaries beneath the skin to the surface is 200 J/s. The energy is transferred a distance of 2.4 x 10^3 m through a body whose surface area is 1.9 m^2. Assuming that the thermal conductivity is that of body fat, determine the temperature difference between the capillaries and the surface of the skin.

Do I use the equation Q=(KA delta T)t/L?

Aghhhh...help please!!

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