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January 10th, 2016, 10:44 AM   #1
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find instantaneous rate of change

for 500g of a radioactive substance with a half-life of 5.2 h, the amount remaining is given by the formula M(t) = 500(0.5)^t/5.2 where M is mass remaining and t is in hours.

Estimate the instantaneous rate of change in mass at 1 day.
I keep getting -2 as the answer. The answer in the book is -0.111. Can someone please show me how to do this? I have no idea what I'm doing wrong.
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January 10th, 2016, 01:21 PM   #2
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I suggest you show us how you did it.
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February 23rd, 2016, 04:54 AM   #3
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Quote:
Originally Posted by rrosa522 View Post
for 500g of a radioactive substance with a half-life of 5.2 h, the amount remaining is given by the formula M(t) = 500(0.5)^t/5.2
You mean M(t)= 500(0.5)^(t/5.2)= $\displaystyle 500(0.5)^{t/5.2}$. What you wrote is $\displaystyle 500\frac{0.5^t}{5.2}$

Quote:
where M is mass remaining and t is in hours.

Estimate the instantaneous rate of change in mass at 1 day.
I keep getting -2 as the answer. The answer in the book is -0.111. Can someone please show me how to do this? I have no idea what I'm doing wrong.
What did you do? Did you differentiate the function? If so what did you get for the derivative?
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