Question

A theory of nuclear astrophysics proposes that all the elements heavier than iron are formed in supernova explosions ending the lives of massive stars. Assume equal amounts of $^{235} \mathrm{U}$ and $^{233} \mathrm{U}$ were created at the time of the explosion and the present $255 \mathrm{V} / 238 \mathrm{U}$ ratio on the Earth is $0.00725 .$ The half-lives of $^{235} \mathrm{U}$ and $^{238} \mathrm{U}$ are $0.704 \times 10^{9} \mathrm{yr}$ and $4.47 \times 10^{9}$ yr, respectively. How long ago did the star(s) explode that released the elements that formed the Earth?

Name: A theory of nuclear astrophysics proposes that all the elements heavier than iron are formed in supernova explosions ending the lives of massive stars. Assume equal amounts of ^235U and ^233U were created at the time of the explosion and the present 255 V / 238 U ratio on the Earth is 0.00725 . The half-lives of ^235U and ^238U are 0.704 × 10^9yr and 4.47 × 10^9 yr, respectively. How long ago did the star(s) explode that released the elements that formed the Earth?
Uploaded: 2022-07-04T01:44:36-08:00
Duration: 5 min 33 s
Channel: Averell Hause

          A theory of nuclear astrophysics proposes that all the elements heavier than iron are formed in supernova explosions ending the lives of massive stars. Assume equal amounts of $^{235} \mathrm{U}$ and $^{233} \mathrm{U}$ were created at the time of the explosion and the present $255 \mathrm{V} / 238 \mathrm{U}$ ratio on the Earth is $0.00725 .$ The half-lives of $^{235} \mathrm{U}$ and $^{238} \mathrm{U}$ are $0.704 \times 10^{9} \mathrm{yr}$ and $4.47 \times 10^{9}$ yr, respectively. How long ago did the star(s) explode that released the elements that formed the Earth?

Added by Rafael A.

University Physics with Modern Physics

Hugh D. Young 14th Edition

Instant Answer

Solved by Expert Averell Hause

07/04/2022

Step 1

00725 = \frac{N_{0,235} \times e^{-0.693/0.704 \times 10^9 t}}{N_{0,238} \times e^{-0.693/4.47 \times 10^9 t}} \] Show more…

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A theory of nuclear astrophysics proposes that all the elements heavier than iron are formed in supernova explosions ending the lives of massive stars. Assume equal amounts of $^{235} mathrm{U}$ and $^{238} mathrm{U}$ were created at the time of the explosion and the present $^{235} mathrm{U} / ^{238} mathrm{U}$ ratio on the Earth is $0.00725 .$ The half-lives of $^{235} mathrm{U}$ and $^{238} mathrm{U}$ are $0.704 imes 10^{9} mathrm{yr}$ and $4.47 imes 10^{9}$ yr, respectively. How long ago did the star(s) explode that released the elements that formed the Earth?