Question 805657
A radioactive substance with an initial mass of 300mg has a half life of 2 years.
a) Write an equation to model the mass of the material over time.
A = 300*2^(-t/2)
:
b) How long will it take for the mass to decay to 1/3 of it's original amount?
300*2^(-t/2) = 100
2^(-t/2) = {{{100/300}}}
ln(2^(-t/2) = {{{ln(100/300)}}}
{{{-t/2}}}*ln(2) = {{{ln(100/300)}}}
{{{-t/2}}}*.693 = -1.0986
{{{-t/2}}} = {{{(-1.0986)/.693}}}
{{{-t/2}}} = -1.585
t = -2 * -1.585
t = 3.17 days