A charge of -2.85 C is fixed at the center of a compass. Two additional charges are fixed on the circle of the compass, which has a radius of 0.108 m. The charges on the circle are -4.3 pc at the position due north and +5.40 pc at the position
due east. What are the magnitude and direction of the net electrostatic force acting on the charge at the center? Specify the
direction relative to due east.

the bal will not change its velocity.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j