Imagine tying a string to a ball and twirling it around you. how is this similar to the moon orbiting the earth? in this example, what is providing the constantly changing, inward force?

Its similar to the moon orbiting the earth because lets say that the sing is moon and the ball is earth has the "moon" orbits around the "earth" the string ends up tying around the ball till its no more

i think i hope this example helps you somehow srry that i dont know more then that :/