Projectile Motion

     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).