petern said:
Well you would do c^2 = a^2 + b^2. Since it is a 45 degree angle, you would do .1/sq. root of 2 for two of the vectors. You would just use .1 m for the third vector. I've plugged in the number and added the 3 together and it doesn't work.
Wait a minute -- let's sort this out first. The distance of the other two charges from the center is
not 0.1/sqrt(2) ; all of the charges are on the same circle. So the magnitude of all of the forces is the same
kQq/(0.1^2) .
What are the x-components (since I see there is a note about that pencilled onto the diagram) for each of the charges? The sum of all the x-components gives you the x-components of the total force.
What happens to the sum of the y-components?
Also, can you help me on the 2nd question?
What they are asking for here is the function of the electric field strength
on the x-axis for all values of x. You have Coulomb's Law,
F = k(q_1)(q_2)/(r^2) ,
to work with. What can you say about the way the fields of the two individual charges point anywhere along the x-axis? That will tell you how to add up the terms that Coulomb's Law will give you for each charge.
Now, there are three regions to think about along the x-axis. They've placed q_1 at the origin (x = 0) and q_2 a distance d to the right (x = d). So you need to look at the intervals
x < d , 0 < x < d , and x > d.
First off, which way do the fields from each charge point in each of those regions?