A hydraulic lift of the type commonly used for greasing automobiles consists of a 10.000-in-diameter ram that slides in a 10.006-in-diameter cylinder, the annular space being filled with oil having a kinematic viscocity of 0.0038 ft^2/sec and specific gravity of 0.83. If the rate of travel of the ram u is 0.5 fps, find the frictional resistance, F when 6 ft of the ram is engaged in the cylinder.