Solve Water Flow in Pipes: Pressure on 2nd Floor

[skier07]

[SOLVED] Water flow in pipes

Homework Statement

Water is circulating through a closed system of pipes in a two floor apartment. On the first floor, the water has a gauge pressure of 3.4 x 10^5 Pa and a speed of 2.1 m/s. However, on the second floor, which is 4.0m higher, the speed of the water is 3.7m/s. The speeds are different because the pipe diameters are different. What is the gauge pressure of the water on the second floor?

Homework Equations

A1V1 = A2V2

P1 - .5(rho)(v1)^2 + (rho)gy1 = P2 + .5(rho)gy2

Efinal = Einitial
KEfinal + PE final = KEinitial + PE initial

Wnc = E1 - E2 = (.5mv1^2 + mgy1) - (.5mv2^2 + mgy2)

The Attempt at a Solution

 

[Snazzy]

Use Bernoulli's equation to solve it. You have what you need.

 

[skier07]

It doesn't matter that the Area changes?..also, I don't know what rho is? do I just use the standard rho of water?

 

[Snazzy]

They've already given you all the information you need. If they asked "find the area of the upper tube" then you would care about the fact that the two velocities are different.

 

[skier07]

what about rho though?

 

[Snazzy]

You know, or should know, the density of water.