Three spheres, each with a negative chrge of 4.0x10^6C, are fixed at the vertices of an equilateral triangle whose sides are 0.20 m long. Calculate the magnitude and direction of the net electric force on each spehere.

Answer 1

Since it is an equilateral triangle and the charges are all the same, you only have to do this once. Because of symmetry, the force on each charge will be a repulsion along a direction that bisects that 60 degree angle of the triangle where the charge is located. The component of the repulsive force due to each of the other two charge along that direction is
k*cos 30* Q^2/a^2
where a = 0.2 m, Q = 4.0*10^6 C and k is the Coulomb's law constant, 9.0*10^9 N m^2/C^2.
Double that force since there are two charges pushing.

It's going to be a suspiciously large number. Are you sure those charges were not 4 microCoulombs?

Answer 2

Thank you, drwls! :)

Answer 3

thank you, drwls! :D

Answer 4

wait, I'm not gtting the correct answer using this, can you please help? I'm getting 3.1N, but I'm supposed to get 6.2N

Answer 5

oh and how can I find the angles as well?

Answer 6

The angles are simple because you have an equilateral triangle. In any triangle, the sum of the internal angles must be 180 degrees. An equilateral triangle is also equiangular. Therefore, the angles are simply 60 degrees each (3 * 60 degrees/angle = 180 degrees)

The two charges will repel each other (as drwls said) along a line that bisects the 60 degree angles. Remember that there are *two* charges repelling each single charge. I think that's why you're getting 3.1 N instead of 6.2N. Multiply by 2.