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### Impulse-Momentum Principle For Fluids Formula

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Impulse-Momentum Principle For Fluids Formula

The Impulse-Momentum Principle is derived from Newton's 2nd law in vector form which states that the rate of change of linear momentum of a body is directly proportional to the external force applied on the body, and this change takes place always in the direction of the force applied.

The resultant force in a given direction acting on the fluid equals the rate of change of momentum of the fluid.

Eq. 1

*∑ F = ∑ Q _{2} ρ_{2} v_{2} - ∑ Q_{1} ρ_{1} v_{1}*

Where:

*∑ F *= the resultant of all external forces acting on the control volume

*∑ Q _{2} ρ_{2} v_{2}* = the rate of momentum of the fluid flow entering the control volume in the same direction
as the force

*∑ Q*= the rate of momentum of the fluid flow leaving the control volume in the same direction as the force

_{1}ρ_{1}v_{1}Source:

Vennard, John K. and Robert L. Street, Elementary Fluid Mechanics, John Wiley & Sons, Inc., 1982.

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