A coin(radius=r) rolls in a funnel only with a horizontal speed v. The coin always stays at his altitude.
The coin has a homogen mass distribution and it only rolls! So it has a translational motion and a rotation motion.
Find a function R(z) whitch discribes the form of the funnel!
R>>r and z is the altitude of the funnel. the z-coordinate of the coin is changeless.



I thougth it must be tan(a)=v²/(r*g)

But then i tought the speed at all parts of the coin isnt the same.

If there are any questions in understand my problem, ask!
I made a drawing of that:


Pls Help me.

I found a vid of my effect.

But i dont know how can i get the form of the funnel. I need a function which discribes the form of the funnel.

In youtube you have to search for coin funnel