1. The problem is to understand and use the Hazen-Williams formula, which is commonly used in hydraulics to estimate the pressure drop or flow rate in pipes due to friction. 2. The Hazen-Williams formula is given by: $$V = k C R^{0.63} S^{0.54}$$ where: - $V$ is the velocity of water in the pipe (ft/s or m/s), - $C$ is the Hazen-Williams roughness coefficient (dimensionless), - $R$ is the hydraulic radius (ft or m), - $S$ is the slope of the energy grade line (head loss per length), - $k$ is a units conversion factor (typically 1.318 for US customary units or 0.849 for SI units). 3. Important notes: - The formula is empirical and valid for turbulent flow in full pipes. - The hydraulic radius $R$ is the cross-sectional area divided by the wetted perimeter. 4. To find the flow rate $Q$, use: $$Q = A V$$ where $A$ is the cross-sectional area of the pipe. 5. This formula helps engineers design pipe systems by estimating flow velocity and pressure losses. Final answer: The Hazen-Williams formula is $$V = k C R^{0.63} S^{0.54}$$ where $V$ is velocity, $C$ is roughness coefficient, $R$ is hydraulic radius, $S$ is slope, and $k$ is a unit factor.