Speed of wave can change if
a) none of the other choices
b) pressure changes
c) temp changes
d) all the other choices
e)enters new medium

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

higher potential

explanation:

because it is in a high speed so it must move into a of high potential

the components of a vector are the parts of the vectors that are to each other.

b perpendicular