In a stadium, fans stand up and sit down to produce a wave across the stadium. this type of wave where the material travels perpendicular to the direction of travel of the the wave. which type of wave does this describe?

a) mechanical wave.
b) transverse wave.
c) longitudinal wave.
d) electromagnetic wave.

if you answer my question i will answer yours

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