Physics Help Forum Water Velocity Out of 200m Pipe at 5 degrees

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Oct 31st 2015, 08:20 PM #1 Member   Join Date: Nov 2010 Posts: 33 Water Velocity Out of 200m Pipe at 5 degrees A resovoir releases water into a 200 meter long pipe with 2m diameter. At 5 degrees relative to x axis so the drop is 200m (sin 5 deg) = 17.4m Since v o is 0 all I can solve for in this veolcity vector: v =(vx^2 + vy^2)^1/2 is for vy = (2gh)^1/2 = 18.4m/sec. Without vx how to solve for vz ? Assume pipe is full. http://www.calctool.org/CALC/eng/civil/hazen-williams_g This format shows a velocity of aboiut 20msec. I am more interested in the solution formula Edit : The acceleration = g sine 5 degrees and v^2 = 2(a*s) So v = (2*sin 5 deg * 9.8m/s^2*200m) ^1/2 =18.5m/s Last edited by morrobay; Nov 1st 2015 at 01:20 AM. Reason: correction
 Nov 2nd 2015, 12:03 AM #2 Member   Join Date: Nov 2010 Posts: 33 Can someone calculate the water pressure in atmospheres at outfall from given data above ? v = 18.5m/sec, 2m diameter full water pipe. Im not familiar enough with Berrnoull'is equation , P = 1/2 pv^2 + pgh = constant p = density
 Nov 3rd 2015, 11:22 AM #3 Senior Member     Join Date: Apr 2008 Location: Bedford, England Posts: 668 There equation P = 1/2 pv^2 + pgh falls fairly obviously into two parts pgh is the pressure due to the height of the water above the outflow p is 1000 kg/lm3 g is 9.8 m/s2 h is 17.4 m 1/2 pv^2 is the pressure due to the motion of the water by your calculations v=18.5m/s __________________ You have GOT to Laugh !
 Nov 3rd 2015, 09:33 PM #4 Member   Join Date: Nov 2010 Posts: 33 The overall question is whether the water from reservoir will drain into ocean from 200 m pipe ,2m in diameter. at 17.5 m depth from pressure differences alone. It seems that the pressure,P, in atm from the pipe from velocity P=1/2 p v^2 is about equal to the water pressure from ocean surroundings at depth of 17.5 meters. P = P(0) + pgh Question : Is the total pressure at submarine outfall equal to the pressure from depth formula AND pressure from velocity formula ? pressure from velocity, 1/2 pV^2 = : 1/2 (1000kg/m^3) 342 m^2/s^2 = 171125 pressure from depth , P(0) + pgh : 1 + (1000kg/m^3) (9.8m/s^2)(17.5m) = 171500 ( does pressure from depth apply to water exiting drain pipe as well as ocean pressure surroundings ? 1 atm = 14.7 lb/in^2 = 101262kg/m^2 Another source said that for every 10m depth add 1 atm pressure. So 17.5 m would 1.75 atm plus one from surface equals 2.7 atm. Last edited by morrobay; Nov 3rd 2015 at 09:39 PM.
 Nov 4th 2015, 06:12 PM #5 Member   Join Date: Nov 2010 Posts: 33 Moderators can you move this to the advanced mechanics dept ? I realize Im having a little confusion on cross-over units here. But thats the reason Im asking the question in the first place. Its sure not about simple multiplication ! Hopefully someone can answer this question even if it requires restating the question.

 Tags 200m, degrees, pipe, velocity, water

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