Apiece of tape is pulled from a spool and lowered toward a 190-mg scrap of paper. only when the tape comes within 8.0 mm is the electric force magnitude great enough to overcome the gravitational force exerted by earth on the scrap and lift it.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

a and c

c is 100% but i am confused in a

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