A valve in the shape of a \(1 / 4\) of a cylinder, made of a material with a density of \(\rho_{\mathrm{z}}=7 \mathrm{~g} / \mathrm{cm}^3\), can rotate around the "O" axis to close a rectangular pipe with a width of \(\mathbf{B}=\mathbf{2} \mathbf{R}\) and a height of \(\mathbf{R}=\mathbf{1 m}\), through which water can flow out of the pool. Determine the value of the force \(\boldsymbol{P}\) necessary to keep the valve in the closed position, if the pool is filled with water to a height of \(3 R\). Assume the density of water to be \(\rho=1 \mathrm{~g} / \mathrm{cm}^3\).