A horizontal nozzle of cross-sectional area \(A\) ejects a continuous stream of fluid of density \(\rho\) at a constant speed \(v_0\). The fluid strikes a hemispherical turbine blade moving horizontally to the right at a constant speed \(u\), where \(u < v_0\). The curved inner surface of the blade smoothly redirects the incident fluid by \(180^\circ\) so that it exits horizontally to the left at a speed of \(v_0 - u\) relative to the blade. In terms of \(\rho\), \(A\), \(v_0\), and \(u\), which of the following expressions represents the magnitude of the average horizontal force exerted by the fluid on the blade?