Aball is released from a hot air balloon moving downward with a velocity of -10.0 meters/second and a height of 1,000 meters. how long did it take the ball to reach the surface of earth? given: g = -9.8 meters/second2.

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