# Choose parameters for a system

1. Oct 21, 2013

### Gh778

Theoretical study. Disks are one above the other. Turn at same rotationnal speed $w$.

Is it possible to choose good parameters for:

- density
- rotationnal speed
- position of d3/gas: d3 in disk1 at radius R1, d3 in disk2 at radius R2, gas in disk1 at radius R2, gas in disk2 at radius R1
- size of disk

For have forces like I drawn on the system ?

NB: disk must be big enouh for have gravity effect (1000 km for example). Center of rotation is supposed fixed.

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Last edited: Oct 21, 2013
2. Jan 16, 2014

### Simon Bridge

No - there are no easy choices of parameter that will produce the results you have drawn.
BTW: the green one is nonsense.

Looking at the blue one:
I can see what you are doing - you think the buoyancy and weight will add to a net tangential force.
Centrifugal gravity does not work like you seem to be thinking.

You realize this is perpetual motion?
Therefore it does not work...

Some notes:
It does not matter how big the disks are - all you need is enough rotation to get the pressure of the liquid to vary with the radius so it is highest at the rim... and you want the blue liquid to be light enough to have zero drag effect.

Make sure you have included all the forces.

3. Jan 17, 2014

### Gh778

Since the time I posted the thread I understood. thanks for your help.