(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Water is supplied to a building through a pipe of radius R = 3.0cm. In the building, a faucet tap of radius r = 1.0cm is located 2.0m above the entering pipe. When the faucet is fully open, it allows us to fill a 25-L bucket in 0.5 minutes. What is gauge pressure in the pipe entering the building? Assume no other faucets are opened during the experiment.

2. Relevant equations

ΔV/Δt = A*v

A1v1 = A2v2

p1 + 1/2ρ(v1^2) = p2 + 1/2ρ(v2^2) (Bernoulli's law)

pgauge = p - patm

3. The attempt at a solution

Using the first two equations I have determined that v1 = 0.3 m/s and v2 = 2.7 m/s. Now I am unsure how to apply Bernoulli's law when I am missing one of the pressures. When I try to use atmospheric pressure (101325 Pa) as one of the pressures, I do not get the correct gauge pressure, which is 23 kPa. I really just need a push in the right direction! Thank you.

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# Bernoulli's law for water coming out of a faucet

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