99 in./s = mi/day Converting rates for 7th grade math can’t seem to figure it out

Two different radioactive isotopes decay to 10% of their respective original amounts. Isotope A does this in 33 days, while isot

Andrews [41]

Answer:

The approximate difference in the half-lives of the isotopes is 66 days.

Step-by-step explanation:

The decay of an isotope is represented by the following differential equation:

$\frac{dm}{dt} = -\frac{t}{\tau}$

Where:

$m$ - Current mass of the isotope, measured in kilograms.

$t$ - Time, measured in days.

$\tau$ - Time constant, measured in days.

The solution of the differential equation is:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$

Where $m_{o}$ is the initial mass of the isotope, measure in kilograms.

Now, the time constant is cleared:

$\ln \frac{m(t)}{m_{o}} = -\frac{t}{\tau}$

$\tau = -\frac{t}{\ln \frac{m(t)}{m_{o}} }$

The half-life of a isotope ( $t_{1/2}$ ) as a function of time constant is:

$t_{1/2} = \tau \cdot \ln2$

$t_{1/2} = -\left(\frac{t}{\ln\frac{m(t)}{m_{o}} }\right) \cdot \ln 2$

The half-life difference between isotope B and isotope A is:

$\Delta t_{1/2} = \left| -\left(\frac{t_{A}}{\ln \frac{m_{A}(t)}{m_{o,A}} } \right)\cdot \ln 2+\left(\frac{t_{B}}{\ln \frac{m_{B}(t)}{m_{o,B}} } \right)\cdot \ln 2\right|$

If $\frac{m_{A}(t)}{m_{o,A}} = \frac{m_{B}(t)}{m_{o,B}} = 0.9$ , $t_{A} = 33\,days$ and $t_{B} = 43\,days$ , the difference in the half-lives of the isotopes is:

$\Delta t_{1/2} = \left|-\left(\frac{33\,days}{\ln 0.90} \right)\cdot \ln 2 + \left(\frac{43\,days}{\ln 0.90} \right)\cdot \ln 2\right|$

$\Delta t_{1/2} \approx 65.788\,days$

The approximate difference in the half-lives of the isotopes is 66 days.

4 0

3 years ago

Read 2 more answers

How much lemonade will each person get if 4 people share 1/2 gallon equally?

Charra [1.4K]

I’m pretty sure the answer would be 8 if u cut 4 in half 4 times

3 0

3 years ago

The value of a car reduces by 30% every 6 months. A car costs $15,000 when new. What is the value of the car after 2 years?

Allisa [31]

6 months goes into 2 years 4 times
30 x 4 = 120
120% of 15,000 is
100% is 1,500
10% is 150
150 x 2 = 300 (20%)
1,500+300=1,800
15,000+1,800=16,800
hope this helped

3 0

3 years ago

Pythagorean Theorem: Jason only has room for a TV that is less than 30” wide.

Tasya [4]

Answer:

No

Step-by-step explanation:

Using the Pythagorean Theorem, make 40 = c, 24 = b and the remaining side (the width) = a.

Solving for a we get a = $\sqrt{c^2-b^2}$ . Then plugging in the values for c and b, we get a = $\sqrt{1024}$ = 32