A pendulum is used in a large clock. The pendulum is raised to its maximum height of 0.3 m and has a mass of 5.2 KG. What is the speed of the pendulum as it reaches its lowest point? A. 4.2 m/s
B. 3.1 m/s
C. 1.9 m/s
D. 2.4 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

higher potential

explanation:

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