posted by R .
Two small, identical metal spheres contain excess charges of -10.0 x 10^-6 C and 6.0 x 10^-6 C, respectively. The spheres are mounted on insulated stands and placed 0.40 m apart. Determine the magnitude and direction of the force between the spheres.
k =9•10^9 N•m²/C²,
q1 =10•10^-6 C (!!! - with "plus" as we use the magnitude of the charge),
q2 = 6•10^-6 C,
r = 0.4 m.
The charges are of the opposite signs => they are attracting.