00:01
Okay, so this one is a little bit of a complex problem.
00:04
We have three point charges arranged as such in space.
00:07
We have two charges that are 2 .5 times 10 to the negative 9 coulumes.
00:12
They're positive.
00:13
One is at negative 0 .5.
00:15
The other one's at 0 .5.
00:16
This here is the origin 0.
00:18
And then we have one on the x -axis, which is 0 .7 meters away from the origin.
00:23
And that one is 3 .0 times 10 to the negative 9.
00:27
And the question is, what is the total force acting on? on this particular charge.
00:33
Now, we're only focused on what's happening on this charge.
00:37
So i'm just going to draw a quick force diagram.
00:41
They're all positive charges, which means they're going to repel each other.
00:44
So this charge is going to feel a force that way from this charge.
00:50
We'll call this one, we'll call this two, and we'll call this three.
00:54
So one on three is going to make it go that way.
00:56
And then two on three is going to make it go that way at the same angle.
01:00
And so that's going to be kind of a setup for later.
01:06
Now, the first thing we have to do is we have to use kulms law, which is force is equal to k constant times q1.
01:14
We'll do one and three first, divided by the separation distance between one and three squared.
01:20
So we're looking for this distance, which we don't know off the top of our heads, but we know this is 0 .5 and we know this is 0 .7.
01:28
So we can actually use pythagram theorem to figure this out.
01:32
So 0 .5 squared, because this is the right triangle.
01:36
So 0 .5 squared plus 0 .7 squared is equal to c squared, or r squared, i guess i should call it.
01:42
And that'll tell us what r is.
01:44
When you plug that in the calculator, you end up getting 0 .86 meters.
01:49
So that's what we're going to use for our r.
01:51
So let's go ahead and calculate this now, the magnitude of the force.
01:55
So k is 9 times 10 to the 9.
01:58
That's a constant that's just given to you.
02:00
The first charge is 2 .5 times 10 to the negative 9.
02:04
And the second charge is 3 .0 times 10 to the negative 9...