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5 votes
The half-life of carbon-14 is 5730 years. A bone is discovered which has 10 percent of the carbon-14 found in the bones of other living animals. How old is the bone?.

2 Answers

3 votes

The bone discovered which has 10 percent of the carbon-14 found in the bones of other living animals is 19154 years old.

The process of carbon-14 decay can be modeled using the exponential decay formula:


\[ N(t) = N_0 \cdot e^(-rt) \]

Where:


\(N(t)\) is the amount of substance at time
\(t\).


\(N_0\) is the initial amount of substance.


\(r\) is the decay rate constant.


\(t\) is time.

Given that the half-life of carbon-14 is 5730 years, we can determine the decay rate constant
\(r\) using the formula for exponential decay:


\[ \text{Half-life} = (\ln(2))/(r) \ \\\\[ r = \frac{\ln(2)}{\text{Half-life}} \ \\\\[ r = (\ln(2))/(5730) \ \\\\[ r \approx 0.00012097 \text{ per year} \]

Now, we're given that the bone has 10% of the carbon-14 found in living animals. This means the remaining amount after decay is 10% of the initial amount
(\(N_0\)).

Let
\(t\) be the time passed.


\[ N(t) = 0.1 \cdot N_0 = N_0 \cdot e^(-rt) \]

Since we know the relationship between the remaining amount and the initial amount, we can set up an equation to solve for
\(t\):


\[ 0.1 \cdot N_0 = N_0 \cdot e^(-rt) \ \\\\[ e^(-rt) = 0.1 \ \\\\[ -rt = \ln(0.1) \ \\\\[ t = -(\ln(0.1))/(r) \ \\\\[ t = -(\ln(0.1))/(0.00012097) \ \\\\[ t \approx 19154 \text{ years} \]

Therefore, the bone is approximately 19154 years old.

answered
User Mark Grey
by
8.2k points
6 votes

Final answer:

The bone is approximately 11,460 years old.

Step-by-step explanation:

The age of the bone can be calculated based on the amount of carbon-14 present compared to the amount found in living animals. Carbon-14 has a half-life of 5730 years. If the bone has 10 percent of the carbon-14 found in living animals, it means that 90 percent has decayed. Using the half-life, we can determine that this decay corresponds to approximately two half-lives. Therefore, the bone is approximately 11,460 years old.

answered
User AMH
by
7.7k points
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