Math Problem Statement

Strontium-90 is a radioactive substance that decays according to the following function, where y0 is the initial amount present, and y is the amount present at time t (in years). y = y0 * e^(-0.024t) Find the half-life of Strontium-90. Do not round any intermediate computations, and round your answer to the nearest tenth.

Solution

The question provides the radioactive decay function of Strontium-90:

y=y0e0.024ty = y_0 e^{-0.024t}

where y0y_0 is the initial amount and yy is the amount remaining after tt years. We are asked to find the half-life of Strontium-90, which is the time required for the substance to reduce to half of its initial amount.

Steps to Solve

  1. Set up the half-life equation: At the half-life t=T1/2t = T_{1/2}, the amount yy will be half of y0y_0: y02=y0e0.024T1/2\frac{y_0}{2} = y_0 e^{-0.024 T_{1/2}}

  2. Divide by y0y_0 (assuming y00y_0 \neq 0): 12=e0.024T1/2\frac{1}{2} = e^{-0.024 T_{1/2}}

  3. Take the natural logarithm of both sides: ln(12)=0.024T1/2\ln\left(\frac{1}{2}\right) = -0.024 T_{1/2}

    Since ln(12)=ln(2)\ln\left(\frac{1}{2}\right) = -\ln(2), we have: ln(2)=0.024T1/2-\ln(2) = -0.024 T_{1/2}

  4. Solve for T1/2T_{1/2}: T1/2=ln(2)0.024T_{1/2} = \frac{\ln(2)}{0.024}

  5. Calculate T1/2T_{1/2}: Using ln(2)0.693\ln(2) \approx 0.693, T1/20.6930.02428.9 yearsT_{1/2} \approx \frac{0.693}{0.024} \approx 28.9 \text{ years}

Answer

The half-life of Strontium-90 is approximately 28.9 years.

Would you like a further breakdown of the calculation steps or have any questions?


Here are some related questions for practice:

  1. What is the general formula for the half-life of a radioactive substance given an exponential decay model?
  2. How would you calculate the remaining amount of a substance after a certain number of years?
  3. If the decay rate was different, say -0.03 instead of -0.024, how would the half-life change?
  4. How does the half-life formula change if the exponential base is different from ee?
  5. Can this decay model apply to other processes besides radioactive decay?

Tip: When working with exponential decay problems, remember that the half-life is independent of the initial amount and only depends on the decay constant.

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Math Problem Analysis

Mathematical Concepts

Exponential Decay
Radioactive Decay
Logarithms

Formulas

y = y0 * e^(-kt)
T1/2 = ln(2) / k

Theorems

Exponential Decay Law

Suitable Grade Level

Grades 11-12