HoW does Newton's cannon thought experiment help with understanding the orbiting of the moon around the earth?

Answer 1

It's difficult to imagine how things stay in orbit, it's all to do with the speed of the object in orbit relative to the ground, and the fact that there is not much air resistance in space to slow a projectile down once it has velocity.

You have to imagine a large cannon on earth that can fire a cannon ball with great speed, from high above the ground (Imagine a cannon on top of a very tall mountain as high as the international space stations orbit for example).

Such ascannon situated at the North Pole for example, will fire a cannonball south, and if given enough power, the cannonball may land near the equator. The cannonball has started off high, but has been pulled towards the earth in that time, causing it to gradually bend or fall into the earth at the point of the equator.

Now consider much more powerful cannon. This time the ball is given so much velocity, that it flies off into space, though the earth's gravity bends it in slightly.

Somewhere between these two power settings is a setting that gives the ball enough velocity to end up back where it was, but since it's in space and there is little air resistance to slow it down, it just keeps going around and around - in orbit.