- #1
jdawg
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Homework Statement
Water flows through a 1.5 [in] diameter pipe. In a 1.5 [ft] section of the pipe water is injected through the porous walls into the pipe at a velocity of 3 [in/s]. What is the average velocity at the exit if the inlet velocity is 6 [ft/s]?
Homework Equations
The Attempt at a Solution
I used 62.4 lb/ft3 for the density of water.
I calculated the area of the pipe to be A=πR2=0.01227 ft3
m1=ρAv=(62.4)(0.01227)(6)=4.59 lb/s
Aw=DL=(1.5/12)(1.5)=0.1875 ft^2 I'm not super confident that this area is correct...
mw=ρAwvw=(62.4)(0.1875)(3/12)=2.925 lb/s
Then I used the conservation of mass...
m1+mw=m2
(4.59)+(2.925)=m2
m2=7.25 lb/s
Now just plug into formula to get vout
vout=(m2)/(ρA)=(7.52)/(62.4*0.01227)
vout=9.82 ft/s
Which is wrong... My options are 7 ft/s, 18 ft/s, 28 ft/s, and 150 ft/s.
I'm not sure what I did wrong!