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New Member
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Aug 21, 2013, 05:45 AM
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What are the age of these bones?
On my assignment I am really struggling with this question...
Bones A and B are x and y thousand years old respectively. A Geiger Counter confirms that Bone A contains 3 times as much C-14 as Bone B. What can you say about the ages of Bones A and B. Justify your answer
The equation used is
a=15.3 x 0.886^t
Thank you in advanced
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Expert
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Aug 21, 2013, 06:00 AM
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You can set up an equation for the ratio of C14 for bone A and bone B:
Now you can manipulate this using logarithms to get an expression for . Post back with what you find and we'll help if you get stuck.
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New Member
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Aug 21, 2013, 06:26 AM
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I am not sure why you have the 3 awkwardly placed in that last line, like I know its times 3 but why is it there? Also do I use lo law and bring the ta and tb to the front?
Thank you so much for your help
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Expert
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Aug 21, 2013, 06:47 AM
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The 3 isn't awkward - it's the ratio of C14 in Bone A (which I called " ") to the amount in Bone B. Thus .
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New Member
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Aug 21, 2013, 06:51 AM
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Oh okay, I understand
So then where do I go from there?
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Expert
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Aug 21, 2013, 06:57 AM
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Hint: take the log of both sides of the equation.
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New Member
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Aug 21, 2013, 07:03 AM
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I think I have it...
I got the answer
Ta/Tb=14.893
Is that correct?
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Expert
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Aug 21, 2013, 07:12 AM
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Originally Posted by cbear12345
I think I have it....
I got the answer
Ta/Tb=14.893
Is that correct?
No, not correct. Please show us the steps you took to get this and we can see where you went wrong.
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New Member
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Aug 21, 2013, 07:14 AM
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ln3=ln15.3(0.886)^ta / ln15.3(0.886)^tb
ln3=ta13.5558/tb13.5558
ln3 x 13.5558= ta/tb
hope that makes sense
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Expert
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Aug 21, 2013, 07:20 AM
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First step is wrong. It's not true that
Instead note that the 15.3 coefficients cancel out, and use the identity:
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New Member
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Aug 21, 2013, 07:33 AM
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ahhh true
so is it
ln3=ta-tb
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Expert
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Aug 21, 2013, 07:45 AM
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Getting closer, but you left out the 0.866 factor...
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What are the age of these bones?
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Hey, I'm doing my maths homework but I'm stuck.
The question goes Bones A and B are x and y thousand years old respectively. Bone A contains 3 times as much carbon-14 as bone B. What can you say about the ages of the bones and justify your answer.
The formula for the carbon-14 is:
a=15.3 x...
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