Question 404: Thermodynamics & KTG

Question

A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2R. The thermal conductivity of the material of the inner cylinder is K
1
and the of the outer cylinder is K
2
. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is :

Accepted Answer

K
eq
= $${{{K_1}{A_1} + {K_2}{A_2}} \over {{A_1} + {A_2}}}$$
= $${{{K_1}\left( {\pi {R^2}} \right) + {K_2}\left( {3\pi {R^2}} \right)} \over {4\pi {R^2}}}$$
= $${{{K_1} + 3{K_2}} \over 4}$$

Answer

K
1
+ K
2

Answer

$${{{K_1} + 3{K_2}} \over 4}$$

Answer

$${{{K_1} + {K_2}} \over 2}$$

Answer

$${{2{K_1} + 3{K_2}} \over 5}$$

Thermodynamics & KTG

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