Abox rests on the (frictionless) bed of a truck. the truck

driver starts the truck and accelerates forward. the box!

immediately starts to slide toward the rear of the truck

bed. discuss the motion of the box, in terms of newton's

laws, as seen (a) by mary standing on the ground beside

the truck, and (b) by chris who is riding on the truck

(fig. 4–35).

i think its

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

technology is the application of the knowledge gained by science.