You decide to launch a ball vertically so that a friend located 45 m above you can catch it. what is the minimum launch speed you can use? how long after the ball is launched will your friend catch it? a. 45m/s b.150m/s c. 30m/s d. 45m/s e. 90m/s

no simpler subs form complex ones. synthesise = make

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