The specific speed (Ns) of a centrifugal pump is given by

• A. <img src="/_files/images/mechanical-engineering/hydraulic-machines/203-138-1.png">
• B. <img src="/_files/images/mechanical-engineering/hydraulic-machines/203-138-2.png">
• C. <img src="/_files/images/mechanical-engineering/hydraulic-machines/203-138-3.png">
• D. <img src="/_files/images/mechanical-engineering/hydraulic-machines/203-138-4.png">