00:01
So what is the generic half -life formula given as? well, let's say it's a of t, where i have t and a is the amount of the substance equals my initial amount times half -life, so i'm multiplying by one -half over time divided by h, which is my half -life.
00:18
Okay, so from this graph, what can i derive? well, first, my initial amount occurs when t equals zero, my initial amount is going to be 50.
00:28
And i also know what's on the substance is after amount of time, 30, maybe days or hours, not sure what the units are, i get 10 of my substance left.
00:41
So 0 .5 times 30 divided by h equals 10.
00:46
So i set up this equation, and i want to solve for my half -life age.
00:50
So what would you do first? well, first i'm multiplying by 50 to this entire term, so let's divide by 50.
00:56
And 10 divided by 50, and my calculators are exactly 0 .2 equals 0 .5 to the 3 divided by h.
01:04
And notice i have an exponent up here.
01:06
How do i get rid of that exponent? well, what's the inverse of the exponential function? well, the logarithment function.
01:13
So i could actually take the natural log because i don't have a log base 0 .5 of both sides.
01:20
I could have also taken the common log...