posted by Tsoanelo .
Three negatively charged sphere, each with a charge of a 4*10^-6C, are fixed at the vertices of an equilateral triangle whose sides are 20cm long. Calculate size and direction of the net electric force on each sphere.
Calculate the force between any two.
Now, look at any vertice. THe forces from adjacent corners are vectors, at 60 deg apart. The force componsnts away from the triangle add, and the force oomponents close to the corners are equal and opposite.
So I see twice the away component.
force away= 2*forcecoulomb*cos30
where force coulomb is the force between any two charges apart .2 m.
sketch it, check my thinking.