Arace driver has made a pit stop to refuel. after refueling, he starts from rest and leaves the pit area with an acceleration whose magnitude is ; after he enters the main speedway. at the same instant, another car on the speedway and traveling at a constant velocity of overtakes and passes the entering car. the entering car maintains its acceleration. how much time is required for the entering car to catch the other car?

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

conservation of mass

mass before something happens = mass afterwards

k2s for potassium sulphide