# Carbon dating "A very old wooden tool"

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#1
The question is to work out the age of the wooden tool. The tool has A carbon-14 activity of 0.07Bq per gram of total carbon content, half life of C-14 is 5700 years and carbon in the atmosphere has an activity of 19 disintegrations per minute.

I worked this out to be 12400 years old but this seems far too old.
I did this by using the equation t(1/2) = ln(A(0)/A)/(lambda); Where t(1/2) = half life = 5700 years, A(0) = initial activity = 0.316Bq = (19/60), A = activity = 0.07Bq and lambda = decay constant = ln(2)/t(1/2).

Any help?
0
4 years ago
#2
it says it is very old.... so why do you think your answer is wrong ?
0
4 years ago
#3
(Original post by frostyfeet)
The question is to work out the age of the wooden tool. The tool has A carbon-14 activity of 0.07Bq per gram of total carbon content, half life of C-14 is 5700 years and carbon in the atmosphere has an activity of 19 disintegrations per minute.

I worked this out to be 12400 years old but this seems far too old.
I did this by using the equation t(1/2) = ln(A(0)/A)/(lambda); Where t(1/2) = half life = 5700 years, A(0) = initial activity = 0.316Bq = (19/60), A = activity = 0.07Bq and lambda = decay constant = ln(2)/t(1/2).

Any help?
use this tool:

https://www.math.upenn.edu/~deturck/.../carbdate.html

to find the % C 14 figure * 0.07/0.316 *100 = 22.15%
1
#4
(Original post by the bear)
it says it is very old.... so why do you think your answer is wrong ?
I'm not sure, it just seems very old and I am not entirely sure if I have calculated initial activity correctly as it's phrased as 19 disintegrations per minute, not decay per second (although I did convert the time).
0
#5
(Original post by the bear)
use this tool:

https://www.math.upenn.edu/~deturck/.../carbdate.html

to find the % C 14 figure * 0.07/0.316 *100 = 22.15%
Thanks for this, it was really helpful.
I checked my answer using this and it looks like it is right as long as I've got the initial activity correct.
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