A mountain climber wears a goose down jacket 3.4cm thick with total surface area
ID: 1391476 • Letter: A
Question
A mountain climber wears a goose down jacket 3.4cm thick with total surface area 1.2m2. The temperature at the surface of the clothing is -18oC and at the skin is 34 oC.
Part A
Determine the rate of heat flow by conduction through the jacket assuming it is dry and the thermal conductivity k is that of down.
Q/t= ______W
Part B
Determine the rate of heat flow by conduction through the jacket assuming the jacket is wet, so k is that of water and the jacket has matted to 0.44cm thickness.
Q/t= ______W
Explanation / Answer
The rate of heat flow by conduction through the jacket assuming it is dry is
Q/t = kA del T /L ( k is thermal condictivity )
= ( 0.025 ) ( 1.2 m^2) ( 34 C - ( -18 C) /0.034 m
= 45.88 W
the rate of heat flow by conduction through the jacket assuming the jacket is wet,
Q/t = kA del T /L ( k is thermal condictivity )
= ( 0.56) ( 1.2 m^2) ( 34 C - ( -18 C) /0.0044 m
= 7.94 * 10 ^3W
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