Half-Life Problem: Solving A0e13K to Get K

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SUMMARY

The discussion focuses on solving the half-life problem for a radioactive substance with a half-life of 13 days. The initial mass of 400 grams decays to 300 grams, requiring the calculation of time using the formula A = A0e(kt). The decay constant K is derived as K = ln(1/2)/13. Participants are guided to substitute known values back into the equation to find the time required for the decay.

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1. Half life of a radioactive substance is 13 days. How long for 400 grams to decay to 300 grams? Solve algebraically and show all work. Give both exact answers and the answer rounded to 4 decimal places.



So I manipulated (1/2)A0=A0e13K to obtain K = ln(1/2)/13

Where do I go from here?
 
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lwelch70 said:
1. Half life of a radioactive substance is 13 days. How long for 400 grams to decay to 300 grams? Solve algebraically and show all work. Give both exact answers and the answer rounded to 4 decimal places.



So I manipulated (1/2)A0=A0e13K to obtain K = ln(1/2)/13

Where do I go from here?

Put your known numbers back in the equation:

A = A0e(kt)
 

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