So basically there is this chart and all you just to name what energy will transform into what energy so like here is just an example like solar to mechanical or something like sorry the arrows are a bit scuffed

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.

It is increased due to the doppler effect. (apex)