1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fluid pressure difference

  1. Dec 1, 2005 #1
    A patient is given an injection with a hypodermic needle 3.2 cm long and 0.25 mm in diameter. Assuming the solution being injected has the same density and viscosity as water at 20°C, find the pressure difference needed to inject the solution at the rate of 1.5 g/s.

    ok I have the equation V = [(P1-P2)(pi*r^4)]/(8*n*L)
    (P1-P2)= pressure difference
    r= .000125 m
    n= .0010055
    L= .032 m
    I do not know how I am suppose to transform 1.5g/s to m/s because im unsure of how to transfer grams to meters.... once i get that I can find the difference in pressure...

    In a similar problem with diameter being .28mm the answer came out to be 320kPa... help???
     
  2. jcsd
  3. Dec 1, 2005 #2

    mezarashi

    User Avatar
    Homework Helper

    Pressure energy is converted into kinetic energy.
    To convert volume flow into velocity, you can consider:

    [tex]\dot{V}= A\cdot v[/tex]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?