An example of a closed system is
, while an example of an open system is.

wvbbvvv

ill do it for 100, also this isnt 80 its 40

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.