m_{k} g = ρ_{v} V g \Rightarrow m_{k} = ρ_{v} V = \frac{π ρ_{v} d^{2} Δ h}{4}

${m_kg = \rho_vVg \quad\Rightarrow\quad m_k = \rho_vV = \frac{\pi\rho_vd^2\Delta h}{4}}$