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: Mixing involving diffy q

  1. Sep 4, 2006 #1
    fluid with 5mg/cm^3 of drug enters bloodsteam at 100cm^3/hr, drug is absorbed by body tissue or otherwise leaves the bloodstream at a rate proportional to the amount present with a rate constant of .4(hr)^-1.

    so assuming the drug is always uniformly distrbuted throughout the bloodstream, the differential equation for the amount of the drug that is present at time t is:

    What i have done is:
    let D(T)=amnt of drug absorbned by the body, at time t (hrs), in mg

    so i got dD/dt= rate in - rate out

    i have the rate in=100(5) mg/cm^3 or 500 mg/cm^3
    and rate out= D(t)/.4

    so my equation is dD/dt= 500-D/.4 then i can just you seperation of varibles...

    what do you all think :grumpy:
  2. jcsd
  3. Sep 5, 2006 #2


    User Avatar
    Science Advisor

    Yes, separation of variables will work. You might also note that that is a "linear differential equation with constant coefficients". Either method will work.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook