Is a motionless liquid-floating object possible?

In summary: Since this is listed as homework, there is probably a model of how nested water/oil containing containers may work - or some hint as to how to build such a model.You should check.
  • #1
Alfreds9
29
1
1. Homework Statement

Do you think it's possible for an object to be relatively motionless if floating on rippled water surface?
Could this be achieved by have it float inside one (or several nested) water/oil-containing containers?

2. Homework Equations

ES = - n2(k-m)2 Lucassen's dispersion for capillary waves at a liquid-air interface3. The Attempt at a Solution

From my (limited) understanding, spilling oil (ugh, poor ecosystems) on water has been a very old trick to dissipate wave energy caused by surface elasticity through the Gibbs-Marangoni effect, however even after scrolling Lighthill's "Waves in Fluids" and reading "The calming effect of oil on water" (Behroozi et al. 2007) I don't yet understand if the tiny amounts measured by Rayleigh (0.81 mg oil spreading on 555 cm^2, or 18mg/square meter) are enough to produce a noticeable dampening effect (compared to a buoy-bound larger amount eventually being thicker) on waves of lower frequencies but larger amplitude (such as those found at sea even on relatively quiet days).

Unfortunately that study doesn't value the attenuation coefficient of mineral oil (which seemed to me like a inert-enough substitute for successive confined-pond experimentation), so if anybody knows which dampening I'd get (or knows of studies on this), I'd appreciate it.

Thank you

Allison
 
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  • #2
Since this is listed as homework, there is probably a model of how nested water/oil containing containers may work - or some hint as to how to build such a model.
You should check.

Personally I would look at things like impedence matching and interference if you want to make a flat regeon, or maybe find a situation where the motion of two objects wrt the mean liquid level will be in phase.
 
  • #3
Simon Bridge said:
Since this is listed as homework, there is probably a model of how nested water/oil containing containers may work - or some hint as to how to build such a model.
You should check.

Personally I would look at things like impedence matching and interference if you want to make a flat regeon, or maybe find a situation where the motion of two objects wrt the mean liquid level will be in phase.

Hi Simon, thanks for your reply.
Unfortunately it's not a real homework but just a project of mine, so I don't have hints to look upon.
Ok I'll look at these.
 
  • #4
What is the reality of the problem ? Can you gives us a sketch and some order of magnitude dimensions ?

There are certainly methods of at least partially stabilising floating bodies in specific situations .
 
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  • #5
Nidum is correct: the answer depends on the specifics.
 
  • #6
Nidum said:
What is the reality of the problem ? Can you gives us a sketch and some order of magnitude dimensions ?

There are certainly methods of at least partially stabilising floating bodies in specific situations .

You're right, of course here it is.

[Questionable link deleted by moderator. See the image in post 9 instead]

Basically just a small-ish floating stand.

Thank you
 
Last edited by a moderator:
  • #7
Please don't click image until mentors have dealt with a reported problem .
 
  • #8
Nidum said:
Please don't click image until mentors have dealt with a reported problem .

I've uploaded it again, hopefully this works now
6rocia.jpg
 
  • #9
There are waves with wavelengths much longer than 20 cm. Your device will follow those waves, the details of its construction do not matter.
 
  • #10
Are you allowed to use a damper? Something like a large horizontal flat sheet of metal on a pole well below the float.
 

FAQ: Is a motionless liquid-floating object possible?

1. Is a motionless liquid-floating object possible?

This is a common question that is often asked by people interested in fluid mechanics and buoyancy. The answer is yes, it is possible for a liquid-floating object to be motionless. This is known as a neutral buoyant condition, where the weight of the object is equal to the weight of the displaced fluid.

2. How does the density of the object affect its ability to float?

The density of an object is one of the key factors that determines whether it will float or sink in a liquid. Objects with a lower density than the liquid will float, while those with a higher density will sink. This is due to the principle of buoyancy, which states that an object will float if the buoyant force acting on it is greater than its weight.

3. Can an object float in any type of liquid?

Technically, an object can float in any type of liquid, as long as its density is lower than that of the liquid. However, certain liquids, such as water, are more commonly used for floating objects due to their availability and properties. Other factors, such as viscosity and surface tension, may also affect an object's ability to float in a specific liquid.

4. What happens to the buoyant force if the object is submerged deeper in the liquid?

As an object is submerged deeper in a liquid, the buoyant force acting on it will increase. This is because the pressure exerted by the liquid on the object increases with depth. However, the weight of the object will also increase, so the object may still remain in a neutral buoyant condition if its density remains the same.

5. Is it possible for an object to float in a liquid without any external forces acting on it?

No, it is not possible for an object to float in a liquid without any external forces acting on it. The buoyant force is an external force that is necessary for an object to float. Without this force, the object would either sink or rise to the surface of the liquid, depending on its density.

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