posted by Mary .
A charge of -3.00 µC is fixed at the center of a compass. Two additional charges are fixed on the circle of the compass (radius = 0.130 m). The charges on the circle are -4.00 µC at the position due north and +5.00 µC at the position due east. What is the magnitude and direction of the net electrostatic force acting on the charge at the center? Specify the direction relative to due east (0°).
Use Coulomb's law to compute the force at the center due to each particle. The -3 uC will exert a repulsion force towards the "South" direction and the +5 uC will exert an attraction force in the East direction. Perform a vector addition of those two forces to get the magnitude and direction.
We don't do problems for people here; we try to help them understand so they can work the problems themselves. I will be happy to critique your work.