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

A first order exponential decay can be written as

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.

## Answer This Question

## Related Questions

- calculus - Carbon-14 is a radioactive substance produced in the Earth's ...
- Science - Radioactive substance decays so that after t years, the amount ...
- Exponential decay - Show that if a radioactive substance has a half life of T, ...
- Maths - A(t)=A'e^(-t/r) where A(t) is the amount after time t, A' is the initial...
- Math - A radioactive substance decays according to the formula Q(t) = Q0e−...
- Math - A radioactive substance decays according to the formula Q(t) = Q0e−...
- physics - a radioactive sample has a decay rate R of 518 decay/min at time t=7 ...
- Differential Equations - Model radioactive decay using the notation t = time (...
- Calculus - a certain radioactive substance is decaying so that at time t, ...
- Calculus-derivatives - Verify if these are correct answers. 1. The derivative of...

More Related Questions