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!

Ammount of plutonium left

  1. Sep 17, 2008 #1
    1. The problem statement, all variables and given/known data

    Plutonium 239 (P-239) decays at a rate of 0.00284 percent per year. If the initial sample size
    of P-239 is 10 g, how much will remain as P-239 after 20,000 years?

    2. Relevant equations

    A=A0e^-rt

    3. The attempt at a solution
    A=10e^-0.00284*20000
    lnA=ln10+lne^-56.4
    lnA=1-56.4
    A=8.7*10^-25
    This answer doesn't seem reasonable and I don't have confidence that I did everything correctly.
     
    Last edited: Sep 17, 2008
  2. jcsd
  3. Sep 17, 2008 #2
    I tried the question again.
    If A=A0*e^-rt
    I want to find A
    If I directly substitute and solve, I'll get..
    A=10e^(-.00284*20000)
    A=2.14*10^-24grams
     
  4. Sep 17, 2008 #3

    hage567

    User Avatar
    Homework Helper

    I think the problem is that you are putting 0.00284 in your equation. The 0.00284 is a percentage. So how else could you express that?
     
  5. Sep 17, 2008 #4
    Its a percentage so .00284 becomes .0000284?
    A=10*e^(-.0000284*20000)
    A=5.66grams
    That sounds more realistic. Is this correct?
     
  6. Sep 17, 2008 #5

    hage567

    User Avatar
    Homework Helper

    Seems reasonable to me.
     
  7. Sep 17, 2008 #6
    Thank you.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Ammount of plutonium left
  1. Plutonium production (Replies: 6)

Loading...