Pressure and fluid head

In equation 2.54 each term represents energy per unit mass of fluid. If the equation is multiplied throughout by density p, each term has the dimensions of pressure and 

If equation 2.54 is divided throughout by g, each term has the dimensions of length, and, as already noted, may be regarded as a component of the total head of the fluid and 

For an incompressible fluid flowing in a horizontal pipe of constant cross-section, in the absence of work being done by the fluid on the surroundings, the pressure change due to 

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