example

A $4-$ft$-$high, $-3$ft $-$diameter cylindirical water tank, whose top is open the atmosplere, is initially filled with water$-$ After the discharge plug near the bottom's pulled out, a water get $40\mathrm{.}5-$in$-$diameter stresses of Vavg. of the jet is approximated as $V=\sqrt[\phantom{2}]{2gh}$ where $h-$ is the water height in the tank rearoed from the center of the hole. Determine how lay it tubs for the water level in the tank to drug to $2$ft from the bottom.