Exponential Functions - Example on Radioactive Decay and Half-Life

in MES Science2 months ago (edited)

A while ago I made a video on exponential functions but didn't get the chance to go over some very useful examples. Which is why I made this video, where I go over an example on radioactive decay and determining the exponential function of Strontium-90 decay if we are given it's half life. I also go over what half life is and show how to determine the required time to decay to a certain mass or the mass after a certain time. This concept is very important especially in dating fossils and other materials and has led to good estimates of the age of the earth. So make sure to watch this video!

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Exponential Functions – Example on Radioactive Decay

Exponential Functions - Examples on Half Life Decay.jpg


The half-life of strontium-90, 90Sr, is 25 years. This means that half of any given quantity of 90Sr will disintegrate or decay in 25 years.

(a) If a sample of 90Sr has a mass of 24 mg, find an expression for the mass m(t) that remains after t years.

(b) Find the mass remaining after 40 years.

(c) Find the time it takes for the sample to decay to 5 mg.