The number of revolution per minute of a ball governor required to keep the balls h inches below the point of suspension varies inversely as the square root of h.

The number of revolution per minute of a ball governor required to keep the balls h inches below the point of suspension varies inversely as the square root of h. If the balls are 6 inches below for 40 revolutions per minute, at what speed will they be 1-1/2 inches below?