
Answer:
F = 144 units
Explanation:
For this exercise we use coulomb's law, for the initial conditions
      F₀ = [tex]k \frac{q_1q_2}{r_o^2}[/tex]
indicate that the force Fâ‚€ = 36.0 units and the distance is reduced to r = râ‚€/2 which is the new force
     F = [tex]k \frac{ q_1q_2 }{(r_o/2)^2}[/tex]
     Â
we substitute
     F = 4 [tex]k \frac{q_1q_2}{r_o^2}[/tex]
     F = 4 F₀
we calculate
     F = 4 36
     F = 144 units