Aboomer is flying at a height of 9km at 800km/h. how far in front of the target should he drop his booms?

What formula  this one  (x_/

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.