One of the main contaminants of a nuclear accident, such as that at Chernobyl, is strontium-90, which decays exponentially at a rate of approximately 2.5% per year.

(a) Write the ratio of strontium-90 remaining, p , as a function of years, t , since the nuclear accident.

Question

One of the main contaminants of a nuclear accident, such as that at Chernobyl, is strontium-90, which decays exponentially at a rate of approximately 2.5% per year.

(a) Write the ratio of strontium-90 remaining, p  , as a function of years, t  , since the nuclear accident.

anonymous · Answer

p(t)=?

a_clan · Answer

If p0 was the initial quantity, then
quantity after time t,
p(t) = p0 (e^ -kt)
The ratio of strontium remaining,p=
p(t)/p0  = (e^ -kt)
             = (e^ -0.025t)

anonymous · Answer

so it's just the last part? e^-....

a_clan · Answer

(e^ -0.025t)

This is required function

anonymous · Answer

ok so p(t)= that

a_clan · Answer

No p(t) = p0 (e^ -kt)

But the given problem is asking the ratio of Sr90 remaining,
So, p= p(t)/p0  is the solution

anonymous · Answer

but it says p(t)=?

a_clan · Answer

That is just a difference of naming convention.
If you want to call the ratio as p(t), then you can name 
'the remaining quantity of Sr90' as , let us say 'pr'.

Then, P(t) = pr/p0 = (e^ -0.025t)

anonymous · Answer

so its the e part i enter

a_clan · Answer

yes the entire e part (exponential part)

anonymous · Answer

okay thanks

a_clan · Answer

np

anonymous · Answer

Sorry, but i just entered e^....and it was wrong

anonymous · Answer

ugh

a_clan · Answer

There are different types of formula for the decay.
y=a(1-r)^t  is also used.

try p(t)=(0.975)^t

anonymous · Answer

but it simply says p(t)= what? so I dont know what to enter.

anonymous · Answer

the e^... was wrong