find the amount of heat that flow in an hour through an aluminium rod,6 cm in diameter and 1.7 m long, if one end of the rod is mantained at a temperature of 120 c and the end at 30 c?(thermal conductivity of aluminium is 240 Wm-1 C)

Question

find the amount of heat that flow in an hour through an aluminium rod,6 cm in diameter and 1.7 m long, if one end of the rod is mantained at a temperature of 120 c and the end at 30 c?(thermal conductivity  of aluminium is 240 Wm-1 C)

anonymous · Answer

nurin,take a look at this link.i'm not sure the answer is accurate or not..but,try to check it out. http://malaysia.answers.yahoo.com/question/index?qid=20110822184508AAWecOl

anonymous · Answer

Q = mc(dT)  However you are mixing up two distinct problems.  The temperature change is 90º.  The mass is volume x density.  Density is around 2,700 kg m-^3. But you have given a U value.  So if it is per metre the diameter doesn't matter.  So it is just 1.7 x 240 x 3600.  As a Watt is a Joule per second.  So the heat energy will be 604,800 J

vincent-lyon.fr · Answer

By analogy with electricity, thermal resistance of the uniform rod is:

$R=\Large \frac {1}{conductivity}\frac{length}{area}$

Thermal resistance applies for steady state which is the case here.

It links thermal power $\Phi$ flowing through the rod and temperature difference $\Delta T$ by:

$\Delta T=R\:\Phi$

Total heat transfer is $Q=\Phi\times time$