[填空题]
A mountain climber wears a goose down jacket 3.5ou)aut + v kb3caa10+x7ok-yj cm thick s/s/86rvn*;yk tdv m f7o8j luwith total surface areas n*tm vsyl86;v j8ofd/ uk/7r $1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down, W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness. W
