Question 5 of 25 What is the speed of a wave that has a frequency of 110 Hz and a wavelength
of 0.21 m?
A. 523 m/s
B. 23.1 m/s
C. 0.04 m/s
D. 0.002 m/s

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

hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.