Ball thrown into a vertical jet?

[topgun08]

Ball thrown into a vertical jet?

Homework Statement

Like any good physicist, I always have a ball in my pocket to throw into
the vertical jet of any fountain I happen to find. The result is entertaining (at least I think
so). Explain, with a sketch, what you expect to see (you need not derive any equations).

The Attempt at a Solution

I'm guessing the ball oscillates up an down...but does it eventually come to rest at its equilibrium position?
Where is the spring force coming from? That is the force that pushes the ball back up once it as gone vertically down on the jet...why doesn't the ball just stay down?

 

[rickster1]

When the water falls back down, the water would fall faster than the ball can fall with the water, depending on the speed of the jet perhaps?

Also, I doubt it ever reaches an equilibrium position, as that would require the water to have an equal spring force in all areas of the jet, while in real life I think the top of the jet is weaker than the middle or the bottom.

I dunno, just throwing in some ideas. I could be wrong..