SORU $62$

$6\mathrm{.}115$ In Fig. P$6\mathrm{.}115$ all pipes are $8-$cm$-$diameter cast iron. Determine the flow rate

from reservoir $(1)$ if valve $C$ is $($a$)$ closed; and $($b$)$ open, with $K_{\text{v}\text{a}\text{l}\text{v}\text{e}}=0\mathrm{.}5.$