F.3 phy,,, conduction. why it is different?

2008-06-02 12:59 am

1. A thicker quilt[綿被] must have a better warmth-keeping ability.
<False>

2.Rate of energy transfer by conduction through a body depends on the thickness of the body.
<True>

how come?!?!

回答 (1)

子路

2008-06-03 8:45 am

✔ 最佳答案

personally (1) is true
for the word "thicker", it can be more cotton or more air trapped inside. the two cases are different
if the answer is <False>, then the only solution is
thicker quilt means more cotton wool
however cotton wool is a better heat conductor than air
so heat is lost at a faster rate

for (2), it is quite difficult
rate of heat transfer = E/t
as heat passes over a conductor, energy is continuously lost
so E is smaller and t does not change

2008-06-07 07:18:59 補充：
amount of heat transfer is reduced by thickness
thus, the rate, E/t is smaller

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