1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Water flow (Concept correct?)

  1. Apr 30, 2009 #1
    1. A hypodermic syringe contains a medicine with a density of water. The barrel of the syringe has a cross-sectional area of 2.5x10e-5 m^2. A force of 2N is exerted on the pluger (left, larger side). Determine the velocity of the medicine as it emerges from the needle

    (1) (2)=====

    2. P1 + 1/2pV1^2 + pghi = P2 + 1/2pV2^2 + pghf

    Area = 2.5x10e-5 m^s, Force = 2 N

    P1 = F/A = 80,000 Pascals

    Because Area decreases, Velocity increases decreasing pressure so we assume P2 = 0, is this correct why we make P2 = 0?
  2. jcsd
  3. Apr 30, 2009 #2


    User Avatar
    Homework Helper

    Inside the syringe pressure in the liquid is sum of atmospheric pressure and pressure due 2N force. Outside the syringe there is only atmospheric pressure.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook