Spinning bottle on the surface of the water

  • #1
10
0
Let us suppose that a cylindrical bottle is on the surface of the water (filled with air for simplicity). A little spin is given to the bottle makes it rotating around the symmetry axis of the cylinder. After a while the bottle stops rotating. How to calculate the time duration of spinning?
 

Answers and Replies

  • #2
35,268
11,536
Anything that looks like a bottle is probably to unstable to keep vertical long enough.
I'm sure a finite-element analysis can give some approximation, and I'm also quite sure that there is no analytic solution to the problem. In a purely theoretical situation, the bottle will get slower and slower without fully stopping.
 
  • #3
Bystander
Science Advisor
Homework Helper
Gold Member
5,203
1,225
Viscous dissipation of the rotational energy will bring it to a full stop. You know the mass of the bottle, it's angular moment of inertia, the initial energy, the viscosity of water, and the surface area of the bottle in contact with the water. From there it's the usual bookkeeping problem.
 
  • #4
35,268
11,536
The water will start moving together with the bottle (but won't do that initially) - and in the absence of external torque, angular momentum conservation will always keep it spinning a bit (at some point it becomes negligible).
 
  • #5
Bystander
Science Advisor
Homework Helper
Gold Member
5,203
1,225
Or, rolling horizontally across the surface.
 
  • #6
35,268
11,536
For a realistic bottle - probably, yes.
 
  • #7
10
0
Anything that looks like a bottle is probably to unstable to keep vertical long enough.
I'm sure a finite-element analysis can give some approximation, and I'm also quite sure that there is no analytic solution to the problem. In a purely theoretical situation, the bottle will get slower and slower without fully stopping.
No, it is not vertical! The axes and the bottle is horizontal!
 
  • #8
35,268
11,536
Ah, okay.
Still, simulations will give some result, it will probably never stop completely, and I am quite sure there is no analytic solution.
 

Related Threads on Spinning bottle on the surface of the water

  • Last Post
Replies
2
Views
2K
Replies
4
Views
2K
Replies
1
Views
3K
  • Last Post
Replies
7
Views
4K
Replies
15
Views
2K
Replies
3
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
9
Views
2K
Top