00:01
All right, i'm going to draw a diagram of what's going on here.
00:05
Speaker 2 is 2 meters behind speaker 1.
00:10
So if i call this point speaker 1 and i call this point speaker 2, and there is 2 meters between them, okay? it then tells us that speakers 1 sound, oops, i should do this in red, is delayed 1 .47 milliseconds.
01:10
Also, the frequency is 340 hertz for both of them.
01:27
And we're supposed to assume that v is 340 meters per second.
01:42
So i'm going to calculate the phase difference between the speakers.
01:54
The sound is delayed.
01:58
Whoops.
01:59
No, actually that's what i wanted to do.
02:02
One, four, seven seconds.
02:09
And what part of a period is that? well, the period is one over the frequency.
02:20
So down here i'm going to put a period.
02:23
Which is 1 over 340 hertz.
02:35
That's going to give me 0 .4998 periods delayed.
02:49
But there are two pi radians in one period.
02:59
So 2 pi times .498, which is really really just 0 .5 is just pi radians delayed.
03:14
So delayed.
03:18
Now we know that this is pi radiance...