00:01
So in question 89, we have two different standing waves.
00:03
So the first standing wave, y1, equals 0 .3, sine is pi 5x minus 500 t.
00:19
And the second standing wave is exactly the same, except that it has an extra phase of plus pi over 3.
00:32
So right now we have y1, y2, and they are travel that combined to produce a traveling wave.
00:41
So we want to understand what is the amplitude, what is wave speed, and what is the wavelength of the new wave.
00:48
So we have, in this section, we learned that when we have two different waves, when they are in the form of ym sine, kx plus omega -t, and when another one has an extra phase difference, plus omega t plus five, we will end up getting a wave that looks something like this.
01:14
2 times ym, cosine 5 over 2, sine, kx plus omega t, plus 5 over 2.
01:29
So this is the equation from this chapter, and this is also obtained.
01:34
You can derive it by using the half angle formula.
01:37
If you think about, if you try to consider this as an angle of sine x plus omega -t plus 5 over 2 minus 5 over 2.
01:46
And try to think of this is plus 5 over 2 plus 5 over 2.
01:51
And then you can divide both these angles as sine a plus b for the first case and sign a minus b for the second case.
01:59
And then you decompose them and you can combine them again.
02:02
If you are not familiar with this process, you might want to go back to the chapter and review.
02:07
This is a formula we get and i think this is also formula 1650.
02:16
This is equation 1650.
02:19
So now let's go back to this actual yyy2 .y5 from this question and ym is 0 .3.
02:27
So we have 0 .6 over here, cosine, 5 is pi over 3, so this is 5 over 6...