Un proyectil se dispara horizontal si el alcance es 290.8 cm y la altura es 190.7 cm; considerando que la gravedad es = /, determine la rapidez de disparo.

i think its c if i'm wrong

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