Exhaust gas from a power plant passes through a $15ft20ft$ rectangular duct at an average velocity of

$50f\frac{t}{s}.$ The total length of duct is $250ft,$ and there are two $90$ bands. The gas is at $180F$ and about $1$atm,

and the properties are similar to those of air. Calculate the pressure drop in the duct. $(25$p$)$

$,$ consider equivalent diameter is large enough to ignore $k(\frac{k}{D}=0),$ at $\frac{k}{D}=0$

$f=0\mathrm{.}0023,K_f$ for band $=0\mathrm{.}9)$

$,$ in ${?}^2$