One of my
favorite and interesting demonstrations with gravity is also proven
with Newtonís three laws. This is when two balls of equal mass
are shot and dropped at exactly the same time. When this is done the
ball that is dropped is expected to hit the ground first before the
one that is shot does but they both fall at the same rate and hit at
the same time as you can see in figure 2. This is because gravity is
acting on the two balls with the same force down. Having them both
falls at 9.8 meters per second has them hit at exactly the same time.
This also applies to a bullet when it is fired and dropped at the
same time in a Newtonian world. But as you can guess it only happens
in a Newtonian world because there is no air friction then. But since
there is air frictional and the bullet is designed not to fall
because of its shape and spin that it is given a bullet that is
dropped will hit the ground before the bullet that is fired will.
This still amazes me every time I see it because the two balls do hit
at the same time (Holliday).