Question

A hallow cubical surface having inside dimensions of lm in which a solid cylinder of diameter 0.5 m and length 0.5m is placed centrally. The shape factor of inside surface of a cubical body with respect to itself is

• A. 0.804
• B. 0.196
• C. 0.5
• D. 0.25

Answer 1

The correct option is A 0.804


$F_{22}=?$

$F_{12}=1$

Using reciprocity theorem

$A_1{F}_{12}=A_2{F}_{21}$

$F_{21}=\frac{A_1}{A_2}\times F_{12}$

$=\frac{\pi DL+2\times \frac{\pi }{4}{D}^2}{6A}\times F_{12}$

$=\frac{\pi \left(0.5\right)\left(0.5\right)+2\times \frac{\pi (0.5{)}^2}{4}}{6\times 1\times 1}\times 1=0.196$

Using summation rule

$F_{21}+F_{22}=1$

$F_{22}=1-F_{21}=1-0.196=0.804$