Two carts on a straight track collide head on. the first cart was moving at 3.6 m/s in the positive x direction and the second was moving at 2.4 m/s in the opposite direction. after the collision, the second car continues moving in its initial direction of motion at 0.24 m/s. if the mass of the second car is 5.0 times that of the first, what is the final velocity of the first car?

0.55x745.7j and a calculator

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