Question

Three identical metal spheres are hung from a ceiling on rigid non-conducting rods. Sphere 1, sphere 2, and sphere 3 have charges
75 µC, −44 µC, and 50 µC, respectively. Each sphere is separated by
0.15 m.


What is the net electric force on the middle sphere due to spheres 1 and 3?

I think it's Coulomb's law:
F = kq1q2/r^2, but not sure.

Please explain in details so i understnad it. thanks

Answer 1

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Answer 2

yes, it is coulomb's law. I assume the charges are left to right, 1,2,3

well the force on 2 from one is to the right(it repulses).
the force on 2 from 3 is attractive, so it is to the right.

So, the easy way is to figure the magnitude of each force, then ADD them, and the resultant is tso the right.