Physics Help Forum Flow in branch pipe

 Thermodynamics and Fluid Mechanics Thermodynamics and Fluid Mechanics Physics Help Forum

 Apr 9th 2016, 09:06 PM #1 Senior Member   Join Date: Jun 2014 Posts: 306 Flow in branch pipe the author stated that Q1= Q2 + Q3 , that's means the water flowing from reservoir A to B and C .... why cant Q1 + Q2 = Q3 ??? which means water flow from reservoir A and B to C ? Attached Thumbnails
 Apr 10th 2016, 04:54 AM #2 Junior Member   Join Date: Feb 2016 Posts: 16 first of all, there are arrows state the direction of the flow. secondly, reservoir A located higher then the other two reservoirs, thus have higher potential energy
Apr 10th 2016, 07:24 AM   #3
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 Originally Posted by shai first of all, there are arrows state the direction of the flow. secondly, reservoir A located higher then the other two reservoirs, thus have higher potential energy
ignore the arrow please.... this is a diagram which have many parts of question... The question that i asked is one of the part only

reservoir 2 also higher than reservoir 3 , why cant water from reservoir 2 flow out ? which means Q1 +Q2 = Q3 ?

 Apr 10th 2016, 04:35 PM #4 Senior Member   Join Date: Jun 2014 Posts: 306 anyone here?
 Apr 11th 2016, 12:38 AM #5 Junior Member   Join Date: Feb 2016 Posts: 16 could be. but if it were so you would get from the energy equations a negative velocity. I suggest you try that assumption, you should get the same result
Apr 11th 2016, 01:34 AM   #6
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 Originally Posted by shai could be. but if it were so you would get from the energy equations a negative velocity. I suggest you try that assumption, you should get the same result
no, i didnt get back the same ans ... i get different ans , how do we know that which is the correct ans ? using method Q1 = Q2 + Q3 or Q1 + Q2 = Q3 ?

 Apr 11th 2016, 01:38 AM #7 Junior Member   Join Date: Feb 2016 Posts: 16 can you post your attempt?
Apr 11th 2016, 03:17 AM   #8
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 Originally Posted by shai can you post your attempt?
i am not sure how to solve the equation though, so i dunno whether my final ans consistent with the author's working or not , can you help it ?

ok , by using online calculator , i found the ans v1 = 1.82m/s , which is same as the author's working. then , what does it mean ? Q1 = Q2 +Q3 ?
or Q1 +Q2 = Q3 ? means water can flow in and out from reservoir 2 at same time or diffferent time ?
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Last edited by ling233; Apr 11th 2016 at 04:20 AM.

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