If an object is not moving, what do we know about the forces acting on it?
they are all positive.
they are all negative.
they are balanced.
they are unbalanced.

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

false.

explanation:

this statement is false. after falling for 5 seconds, its speed will not be 100 m/s.