Alight string is wrapped around the edge of the smaller disk, and a 1.50-kg block, suspended from the free end of the string. if the block is released from rest at a distance of 1.99 m above the floor, what is its speed just before it strikes the floor?

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

prndulum needs thread, weight clock to time swings