00:01
For this problem on the topic of electric fields, we have a charged cork ball which has a mass of 1 gram and is suspended on a light string in the presence of a uniform electric field.
00:10
We are given the electric field and we are told that the angle theta is 37 degrees for the ball in equilibrium.
00:17
We want to find the charge in the ball as well as the tension in the string.
00:22
Now we've drawn a free body diagram for the ball with charge q and we want to find the charger q.
00:32
And we can first use newton's second law and show that the resultant force in the horizontal direction, which is the sum of the x force components, is q times ex minus t sine theta.
00:52
And we know this must equal to zero since the ball is in equilibrium.
00:58
If we do the same for the vertical force components, we get this to be q, ey, the y component of the electrostatic force plus t times the cosine of theta, which is the y component of the tension, minus the weight of the ball, mg.
01:18
And again, this must equal to zero.
01:21
So we'll call this equation two...