A uniform rectangular plate is hanging vertically downward from a hinge that passes along its left edge. By blowing air at 9.70 m/s over the top of the plate only, it is possible to keep the plate in a horizontal position, as illustrated in part a of the drawing. To what value should the air speed be reduced so that the plate is kept at a 30.0° angle with respect to the vertical, as in part b of the drawing?