Friday

September 19, 2014

September 19, 2014

Posted by **Beth** on Saturday, October 11, 2008 at 10:12am.

A(t)= Ae^(-t/r)

where A(t) is the amount (of substance) after time t, A is the initial amount at time t=0 and r is the decay time.

The fall time is defined as the time in which A(t) falls from 90% to 10% of its initial value. Find the relationship between the fall time of an exponential decay and r.

- Physics -
**bobpursley**, Saturday, October 11, 2008 at 11:53amI will start it off

.9=e^t1/r

ln .9 = t1/r

likewise..

ln .1=t2/r

tfall=t2-t1, well you do that...

**Answer this Question**

**Related Questions**

calculus - Carbon-14 is a radioactive substance produced in the Earth's ...

Maths - A(t)=A'e^(-t/r) where A(t) is the amount after time t, A' is the initial...

Alegbra - Andrew measures the amount of a very unstable substance to be 100 ...

Science - Radioactive substance decays so that after t years, the amount ...

Math - A radioactive substance decays according to the formula Q(t) = Q0e−...

Math - A radioactive substance decays according to the formula Q(t) = Q0e−...

algebra - Andrew measures they amount of a very unstable substance to be 100 ...

hard math question - When a certain drug enters the blood stream, its potency ...

Exponential decay - Show that if a radioactive substance has a half life of T, ...

math - i have this question and im not sure how to do it i keep getting stuck ...