7 . Choose the correct answer Hydraulic resistance of a vessel (tube)) is determined by the formula: X=(8eta l^2)/(pi R) X=(8eta l)/(pi R) X=(pi R)/(8eta l) X=(8eta l)/(pi R^4) X=(pi R^4)/(8eta l)

The correct answer is:<br />$X=\frac {8\eta l}{\pi R^{4}}$<br /><br />Explanation:<br />The hydraulic resistance of a vessel (or tube) is determined by the formula $X=\frac {8\eta l}{\pi R^{4}}$, where $X$ represents the hydraulic resistance, $\eta$ is the dynamic viscosity of the fluid, $l$ is the length of the vessel, and $R$ is the radius of the vessel. This formula takes into account the effect of the fluid's viscosity and the vessel's dimensions on the resistance to flow.