A boy is at rest on a slide sloped at 22°. The coefficient of kinetic friction between the boy and the slide is 0.12. The boy starts down the slide. What is the acceleration?

which statement about this sum is true? −245+2.7

neither accurate nor precise.

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

3. dark matter

empty space could also be a simple vacuum