00:01
I'm going to go ahead and draw the picture at t equals zero.
00:10
There is a wall here, and we count up to eight, four, eight.
00:27
Okay.
00:30
Now, the pulse on the left goes from one to three, from one to three, and it has an amplitude, a height at least of two.
01:04
And it is moving to the right.
01:08
The other one is also moving to the right.
01:11
I'm going to make that a green one.
01:13
It goes from five to six, only has a height of one, moving to the right.
01:37
Now, the reason why we are told that it is fixed at eight meters is because there is going to be a reflection with an inversion when it reaches 8 meters.
01:56
So let's go to t equals 2, because we've got to do 2, 4, 6, and 8.
02:07
So at t equals 2, it looks like i've got to draw this again.
02:26
T equals two.
02:28
Okay, the red one is going to move over two because the speed is one meter per second.
02:34
One meter per second for two meters is, for two seconds is two meters.
02:40
One meter per second for two seconds equals one meter.
02:47
Okay, so, no, two meters.
02:49
It's going to go over two meters.
02:51
It used to be at one.
02:52
So now it's going to be at, going to be at three.
02:59
So it's going to extend from three to five.
03:03
The other one is going to extend from, it used to be at one, two, three, four, five.
03:19
So now it's going to be at seven.
03:25
So one, two, three, four, five, six, seven.
03:40
So that's going to go from seven to, to eight and we see no superposition.
03:52
Let's keep going.
03:57
T equals four.
04:05
All right.
04:15
The red one is going to go two more.
04:17
So that's going to go from here to here up to two.
04:25
The green one is going to go two more.
04:28
So if we count, if we take a look at this right here, is zero, one, and then back to two.
04:41
So it's going to hit and then come right back, but it's going to invert as well.
04:47
And so it's going to look like this.
04:52
So when we add these two waves together to create the combined wave, no addition that, oops, trying to use blue here, no addition there, no addition there, no addition there.
05:23
So we see that this stays the same and this stays the same.
05:29
However, at this point, we do see some addition.
05:46
Right here, this value here is halfway between one and two of displaced, i mean, between, zero and two on displacement.
05:55
So this is a one centimeter displacement.
06:00
So the height of this is one centimeter.
06:03
One.
06:04
This is two.
06:09
The height of the green one is also one centimeter.
06:12
So i have this drawn a little bit out of scale.
06:17
So let me redo this...