00:01
Let's analyze all the forces on the left point chart.
00:05
There is gravity point downward, and the magnitude of gravity equals to the mass times the gravity constant, and we get that the gravity is about 4 .9 times 10 to negative 2 neuters.
00:26
And there is electric force, exerted by the other point charge point to the left.
00:35
We call it fe.
00:38
And the magnitude of this fe could be calculated with the formula k times q square over the square of their distance.
00:50
And what's their distance? their distance r should equal to 1 meter times sine theta, which gives us half of their distance and times 2.
01:04
Okay? and we substitute this into this equation, and we'll get that the magnitude of fe is 2 .25 times 10 to negative 5 over the square of sine theta newton.
01:23
And there is a third force on this point charge given by this thread.
01:32
So i will call this t, the tension.
01:36
And these three forces cancel out each other.
01:43
So we can get that the t times the x component...