00:01
All right, so we have two objects, a and b, that are positively charged.
00:05
So they have charges qa and qb.
00:10
And they have the same mass.
00:12
So the mass of a is equal to the mass of b, which we'll just call m.
00:17
And this is half a kilogram or 500 grams.
00:21
And let me rewrite that m.
00:25
And what we want to know is if they're placed 25 centimeters apart, or when they're placed 25 centimeters apart, so 0 .25 meters.
00:39
The particle b, charge b, experiences an electric force of 0 .35 newtons.
00:48
And so then we want to know what is the charge on a, given that a has twice the charge of b.
00:54
So we have qa equals 2qb.
01:00
Well, the force, according to kulam, is the charge on a times the charge on b, times kulam's constant, divided by the distance between them squared.
01:11
And we have that equal to 35 newton's.
01:14
And we also have a relationship between k -a and qb.
01:18
So if we substitute in the fact that qa is twice qb, or actually we're solving for qa.
01:24
So we'll write qa, and qb is half of qa...