For a top player, a tennis ball may leave the racket on the serve with a speed of 160 m/s. If the ball has a mass of 0.080 g and is in contact with the racket for about 5 ms (0.005 s), estimate the average force on the ball.

answer: the answer is a

the bal will not change its velocity.

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

answercollision;