Prob. $2\mathrm{.}8\mathrm{.}43$ p$.$ IP$-24[$Ans: $1\mathrm{.}88ft].$

$2\mathrm{.}8\mathrm{.}43$ WP SS A thin $4-$ft$-$wide, right$-$angle gate with negligible mass is free to pivot about a frictionless hinge at point $O,$ as shown in Fig. P$2\mathrm{.}8\mathrm{.}43.$ The horizontal portion of the gate covers a $1-$ft$-$diameter drain pipe that contains air at atmospheric pressure. Determine the minimum water depth, $h,$ at which the gate will pivot to allow water to flow into the pipe.

FIGURE P$2\mathrm{.}8\mathrm{.}43$