The law of conservation of energy applies:
a. whenever pe = 0.
b. in isolated systems.
c. in all systems
d. only in open mechanical systems.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach