00:01
So we're told that we have this string instrument, and it's got a length of 60 centimeters when you're not putting your fingers down on the bridge.
00:10
I'm going to call this la for reasons that will become clear.
00:13
And we're told that this length, it produces a fundamental frequency of 440 hertz.
00:20
And we're also given another piece of information that the string mass is 2 grams.
00:26
So we're told that this is the frequency for an a that we're producing here, an a4.
00:32
And we want to know where we need to put our finger to produce a g, which has, that looks like a 6.
00:43
Fg.
00:45
One more time.
00:47
There we go.
00:50
Actually, it's actually fd here in this part, of 587 hertz.
01:01
So we know for a string, the velocity of the wave propagation is a constant.
01:06
It's just based on the material.
01:07
So we know that v is equal to lambda f.
01:12
And so if we can solve for v in terms of the information we're given about the a note, then we can translate that and solve for the length required for the d note.
01:23
So we know that on the fundamental frequency, l is equal to lambda over 2...