Answer:
-6.95*10^-17 J
Explanation:
Given that
Magnitude of first charge, q1 = 3.9*10^-9 C
Magnitude of second charge, q2 = 1.85*10^-9 C
Distance between the two charges, r = 30 cm = 0.3 m
The potential energy of point charges is given as
U = kqq•/r, where
k = constant of proportionality, 8.99*10^9 Nm²/C²
See attachment for solution.
At the part I tagged B, the distance of the second charge 30 cm - 10 cm, and that is how I got my 20 cm or 0.2 m as I used it.
The final answer would have been
U = U1 + U2
U = -5.62*10^-17 + -1.33*10^-17
U = -6.95*10^-17 J
