Results 1 to 3 of 3

Math Help - Half Life Question

  1. #1
    Newbie
    Joined
    Apr 2009
    Posts
    16

    Half Life Question

    The radioactive isotope uranium-232 has a half-life of 68.9 years.

    The decay constant of uranium-232 is

    If you have 35 grams of uranium-232 to begin with, the equation that describes the radioactive decay is

    Help please!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor chisigma's Avatar
    Joined
    Mar 2009
    From
    near Piacenza (Italy)
    Posts
    2,162
    Thanks
    5
    By definition 'half time' is the time in which a mass of material subject to decay [Uranium for example...] is halved. The decay law is then...

    m(t)=m_{0}\cdot 2^{- \frac{t}{t_{h}}}

    ... where t_{h} is the 'half time' and m_{0} the mass of material at the time t=0...

    Kind regards

    \chi \sigma
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Chicago, IL
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by v3ndetta View Post
    The radioactive isotope uranium-232 has a half-life of 68.9 years.

    The decay constant of uranium-232 is
    Recall that T_{1/2}=\lambda=\frac{\ln 2}{k} where T_{1/2} (interchangeable with \lambda) is the half life, and k is the decay constant. Thus, k=\frac{\ln 2}{68.9}\approx\boxed{.0101}

    If you have 35 grams of uranium-232 to begin with, the equation that describes the radioactive decay is

    Help please!
    Now that we have k, we can set up our equation.

    The decay equation has the form y=y_0e^{-kt}, where y_0 is the initial amount of the substance.

    Thus, our decay equation is \boxed{y=35e^{-.0101t}}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Half Life Question
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: January 23rd 2010, 06:40 PM
  2. logarithmic half life question
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 25th 2009, 01:33 PM
  3. Half - Life Question!
    Posted in the Calculus Forum
    Replies: 2
    Last Post: October 2nd 2009, 09:28 PM
  4. Half-Life Question
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: June 20th 2009, 01:25 PM
  5. Half life question
    Posted in the Pre-Calculus Forum
    Replies: 6
    Last Post: June 17th 2009, 09:20 PM

Search Tags


/mathhelpforum @mathhelpforum