# Venturi tube help needed in determining pressure difference

by timothy1875
Tags: determining, difference, pressure, tube, venturi
 P: 9 1. The problem statement, all variables and given/known data Water flows through venturi tube at 0.3 litres/s. Diameter of venturi tube is 32mm to 20mm to 32mm and the water density is 1000kg/m^3. 2. Relevant equations a) Assuming head loss is neglible, what is pressure difference between 1 and 2. b) If pressure head difference between these is 45mm what is head loss. 3. The attempt at a solution So far I have V2 = P1A1V1/P2A2 = 0.9548 and V1 (Q/A) = 0.3731 delta H 1/2 = H1 - H2 = 1/2g (V2^2-V1^2)) delta H 1/2 = 39.3mm Where do I go from here, if this is even correct ? Thanks a lot for your help.
 Sci Advisor HW Helper Thanks P: 26,160 hi timothy1875! welcome to pf! (try using the X2 and X2 icons just above the Reply box ) i don't follow you … use the fact that the volume per time is constant, and Bernoulli's equation
 P: 9 Hi Tim, Thanks for getting back to me.I am trying to answer the question but think I may be going about it the wrong way. Using the Bernoulli equation do I need to transpose to find P ?
 Sci Advisor HW Helper Thanks P: 26,160 Venturi tube help needed in determining pressure difference show us what you have so far
 P: 9 V2 = P1A1V1/P2A2 = 0.9548 and V1 (Q/A) = 0.3731 delta H 1/2 = H1 - H2 = 1/2g (V22-V12) delta H 1/2 = 39.3mm This where I have got to so far, :(