Imagine a mountain so high that its peak is above the atmosphere of the earth. Imagine on top of that mountain a cannon, that fires horizontally. As more and more charge is used with each shot, the speed of the cannonball will be grater, and the projectile will impact the ground farther and farther from the mountain. Finally, at a certain speed, the cannonball will not hit the ground at all. It will fall toward the circular earth just as fast as the earth curves away from it. In the absence of drag from the atmosphere, it will continue forever in an orbit around the earth. More...