00:01
All right, so let's say we have four charges, point charges, that all have a charge of one microcoulomb in a mass of one gram.
00:10
And they're all spaced a distance, we'll call this a, which is 10 centimeters apart.
00:15
So we want to know what's the initial potential energy of the system.
00:21
So this will be basically the sum over all pairs that we have.
00:26
So we'll have three nearest neighbor pairs.
00:28
So this will be three times k times q squared over a, right.
00:33
And then we have the pairs that are two, a distance of two a apart.
00:38
So we have two of those, so two k q squared over two a.
00:42
And then we have one pair that is three apart, so k q squared over three a...