00:02
Sound intensity varies inversely as the square of the distance from the source of the sound.
00:08
I'm going to start by coming up with our variation equation.
00:11
What isn't it called the sound intensity i? and we'll say i, since it varies inversely, it's equal to k divided by the square of the distance.
00:21
There's your distance squared.
00:24
What reen asked is, if we're in a theater and we move to a new seat that's twice as far away, how does the new intensity compare? so here's what we're going to do.
00:33
I'm going to show you in general how it works, and then we'll plug a number in, or analyze a number, just to see how that works.
00:41
So, if we double the distance away, what this turns into is i equals k over twice the distance squared.
00:52
Notice that 2 is in the quantity being squared.
00:55
Now, this is going to simplify down into k over 4d squared.
00:59
The reason that works is when we do 2d times itself.
01:04
The order of all this multiplication doesn't matter...