A sphere moves horizontally through still water at a speed of 11 ft/s. A short distance directly ahead of the sphere (call it point a), the velocity, with respect to the earth, induced by the sphere is 1 ft/s in the same direction as the motion of the sphere. If Po is the pressure in the undisturbed water at the same depth as the center of the sphere, then the value of the ration Pa/Po will be a) less than unity, b) equal to unity, or c) greater than unity?