Critical Speed C067.
Any object made of an elastic material has a natural period of vibration.
At the speed at which the centrifugal force exceeds the elastic restoring force, the rotating element will vibrate as though it were seriously unbalanced. If it runs at that speed without restraining forces, the deflection will continue until the shaft fails. We use this formula to make comparisons between competitor pumps specified for the same application. We do this by eliminating the non variables from the formula. The force on the shaft will be the same in the designs we are comparing.