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Homework Help: Rate of Decay

  1. Mar 2, 2010 #1
    Hi.
    We are given a table containing values of mass(m) and time(t). We have been asked to plot graphs of (m) against (t) and then log(m) against (t).

    The question is:
    FROM YOUR GRAPHS, DETERMINE THE FUNCTION FOR THE RATE OF DECAY.

    Of course i know the formula but have no clue how to derive that. i need some help.
     
  2. jcsd
  3. Mar 2, 2010 #2
    when you say rate of decay are you referring to the half life? and you dont need to derive it but just say how your data supports it. Do you have any more specific information on your problem? such as your results for the m vs t and log(m) vs t?
     
  4. Mar 2, 2010 #3
    sorry, for the "rate of decay" im referring to the formula m=m(0)*e^-kt

    I have the following info when plotted log(m) vs t:
    It is a straight line graph,
    c(log(m) intercept) = 4.5
    gradient = -0.25
     
  5. Mar 2, 2010 #4
    so what would be your rate of decay from the graph?
     
  6. Mar 2, 2010 #5
    Hi,
    do you about the relations between meanline, halflife, decay rate and their invese..?
    Just relate then and see you will get the answer.
    You can also do a exponential fit for your plot!
    good luck
     
  7. Mar 2, 2010 #6
    thats what i need help with
     
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