Two charged objects attract each other with a certain force. if the charge on one of the objects is doubled with no change in the other or the separation, the force between them
a.) quadruples
b.) doubles
c.) halves
d.) increases, but we can't say how much without knowing the distance between them

i think it's 35 meters

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