00:01
Consider the following configuration of charges.
00:03
We have q1, q2, and q3.
00:06
We only want to find the net force on q2.
00:10
First, let's recall the kool -on force.
00:24
So the force between two charges is similar to the gravitational expression.
00:29
It's given by k, the equivalent constant, times q1, q2, an absolute value, divided by r squared.
00:41
So this is the magnitude of the clonon force.
00:44
And afterwards, considering our geometry, we could compute the unit vector to obtain the vector force.
00:58
We're going to need this because we're going to make an addition of forces or a superposition of forces.
01:06
Over here, our coulum constant is roughly equal to 9 times 10 to the power of 9 newton meter square over coulon square.
01:23
So let's draw our forces involved.
01:26
So q1 is a negative first, that's going to attract q2, which is a positive, excuse me, q1 is a negative charge, which is going to attract q2, which is a positive charge, along this direction.
01:39
I will call this f1.
01:49
Q3 is positive, which means going to repel q2, which is another positive charge along this direction.
02:00
And then, that force, q3, uh, f3.
02:10
To compute f1, we're going to need a distance, so r here, the distance between two charges.
02:14
We're going to need this distance right here.
02:34
This is our, i'll call this r1.
02:46
We can find r1 pretty easily with a little bit of trigidometry.
02:53
So, we have that f1 is given by k times q2 times q1, divided by r1, where r1 is equal to the square root 200 centimeters square plus 300 centimeters square, yielding a distance or separation between the two charges of roughly 390 .51 centimeters.
03:54
So here we're getting centimeters.
03:56
We want to be careful because we're going to need to insert meters because our kulam constant is in meters.
04:06
So we obtain 9 times 10 to power.
04:10
9 times 5 times 10 to the power of minus 9.
04:19
This is for q2 nanometers, times 12 times 10 to the power of minus 13.
04:33
Divided by, oh, is the squared here.
04:41
3 .90 squared...