A 1550 kg torpedo strikes a 770 kg target that is initially at rest. If the combined torpedo and target move forward with a speed of 9.44 m/s,
what is the initial velocity of the torpedo? Assume that no resistance is
provided by the water.

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

answercollision;