electromagnetic, gravitational & atomic forces
Lack of motion or lack of CHANGE in motion does not mean forces are not being applied.
Acceleration = change in speed (faster or slower) or direction.
drop a paper flat vs. vertical: less air molecule resistance when vertical, so it falls faster (less friction) Is it easier to slide across a hard, polished floor or carpet?
drop a paper flat vs. vertical: less air molecule resistance when vertical, so it falls faster (less friction) Is it easier to slide across a hard, polished floor or carpet? * Adhesion can sometimes increase friction, esp. in fluids