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: Thermodynamics Conceptual Question

  1. Mar 18, 2010 #1
    1. The problem statement, all variables and given/known data

    I have a system with air flowing through a ducting with two inlets and one exit operating at steady state. There is no heat transfer or potential energy change. I know the mass flow rates and velocities at all inlets and exits. How would I go about finding the rate of change in kinetic energy for the stream flowing from point 2, an inlet, to point 3, the outlet.

    2. Relevant equations

    3. The attempt at a solution

    I don't know exactly what the rate of change of kinetic energy between one of the inlets and the exit means, so I don't know where to start.
  2. jcsd
  3. Mar 23, 2010 #2
    Maybe the rate of change in the kinetic energies of the inlets and outlet per minute or second? [tex] K.E. = \frac{1}{2}mv^2[/tex]
    Last edited: Mar 23, 2010
  4. Mar 23, 2010 #3


    User Avatar
    Homework Helper

    Adding to what crims0ned suggested

    [tex]\frac{d}{dt}(KE) = \frac{1}{2} \dot{m}v^2[/tex]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook