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## Homework Statement

fluid is flowing upward through a 1cm diameter pipe at 0.15m/s find the necessary power per unit length to drive the flow through the pipe.

## Homework Equations

tau= (viscosity)dU/dy

flux of momentum out - flux of momentum in= forces acting on the CV (tau( downward) and F_y( upward))

force x velocity = power.

## The Attempt at a Solution

I found all the forces acting on the CV:

shear stress

and F subscript y

I ignored the weight as it might already be contained in the Force y which pushes the flow upward and also because I have no idea what the mass of the water would be here.

in this case mom in= mom out => tau( shear stress)*A=F_y

tau= 0.03006 Pa

tau*A=7.85*10^-5N= F_y

=> F_y*U( velocity)=1.17809*10^-5 J/S