Question

A coca-cola bottle is whirled in a horizontal circle of radius r as shown in Fig. where will the gas stay:

• A. at the neck
• B. in the middle
• C. at the bottom
• D. anywhere

Answer 1

The correct option is C at the bottom

F=mr${\omega }^2$ the smaller the mass, the more is the radius to maintain the same force.
Note this is the principle of cream separator from milk centrifuge machines used in laboratories and even the Earth is built in the same way. Heaviest masses close to the axis and the lightest at the surface.

Due to centrifugal force, the very light gas will have to maintain large radius so it will accumulate at the bottom.