A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 5 years ago
The halflife of a certain radioactive element is 10 years. How much of a 20g sample
will be left after 8 years? (Hint: first find the decay constant.)
anonymous
 5 years ago
The halflife of a certain radioactive element is 10 years. How much of a 20g sample will be left after 8 years? (Hint: first find the decay constant.)

This Question is Closed

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[ N(t) = N_0 e^{\lambda t}. \, \] use this, substitute the values in, and you will get the decay constant

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I already used 10 = ln(2) / k > ln(2) / 10 = k. But then what?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Then I got A = 20e^((ln(2)/10)10). What's next? where do the 8 years come in?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok, the amount of radioactive element left after 8 years will be amount remained =20/(2(8/10)) =12.5g

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0where'd you get the 20 from?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0ok, what does halflife mean in the first pace? it is 10 years, meaning that after 10 years the amount will become smaler by a factor of two, that is we need to divide it by 2, but since we only wait 8 years, which is 8/10 or 0.8 of the half life,we have to multiply the half life by the ratio 0.8 to 1 so, it is 2*0.8=1.6, so after 8 years, the sample reduses by a factor of 1.6

dumbcow
 5 years ago
Best ResponseYou've already chosen the best response.0Use the equation posted at the top and use t=8, k = ln(2)/10, N_0 = 20 Answer should be around 11.49 rounded
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.