Buoyant Force in High vs Low Density Liquids: Homework Statement & Solution

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SUMMARY

This discussion centers on the stability of floating objects in liquids of varying densities, specifically comparing high-density and low-density liquids. The buoyant force, calculated using the formula F_b = ρVg, remains constant for an object floating in both types of liquids, as it must equal the object's weight. However, the stability of the object increases when it is more submerged, which occurs in higher density liquids. The conversation emphasizes the importance of understanding buoyancy and stability in fluid mechanics.

PREREQUISITES
  • Understanding of buoyancy principles
  • Familiarity with the formula for buoyant force (F_b = ρVg)
  • Knowledge of density and its effects on floating objects
  • Concept of stability in floating bodies
NEXT STEPS
  • Research the concept of metacentric height and its impact on stability
  • Explore the relationship between density and buoyancy in different fluids
  • Study the effects of shape and volume on the stability of floating objects
  • Learn about Archimedes' principle and its applications in fluid mechanics
USEFUL FOR

Students studying physics, particularly those focusing on fluid mechanics, as well as educators teaching concepts related to buoyancy and stability in liquids.

  • #31
haruspex said:
Yes, that would generally be true.
So, the reason that the object is less stable in more dense water is because when the object float higher in liquid, it has more tendency to turn over?
 
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  • #32
chetzread said:
So, the reason that the object is less stable in more dense water is because when the object float higher in liquid, it has more tendency to turn over?
Yes. But as I posted, that is only the general trend. There may be exceptions according to shape.
 
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  • #33
haruspex said:
Yes. But as I posted, that is only the general trend. There may be exceptions according to shape.
Exception according to shape? Can you explain further?
 
  • #34
The trick is to realize what gives rise to the stability.
To do that, draw the same shape in two different liquids, as per my example to start with, then do another sketch with them a bit tilted over.
Look to see where the forces act (hint: pressure is perpendicular to the surface, and the pressure at the sides is also important.)

Do you understand where the buoyancy force comes from in the first place?

(I know I said "tomorrow but I have insomnia - and I saw post #25 before post #24 for some reason.)
 
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  • #35
Simon Bridge said:
The trick is to realize what gives rise to the stability.
To do that, draw the same shape in two different liquids, as per my example to start with, then do another sketch with them a bit tilted over.

Look to see where the forces act (hint: pressure is perpendicular to the surface, and the pressure at the sides is also important.)

Do you understand where the buoyancy force comes from in the first place?

(I know I said "tomorrow but I have insomnia - and I saw post #25 before post #24 for some reason.)
Here it is, so what are you trying to say?
 

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  • #36
is there anything to do with the metacentric height , buoyant point in this question ?
 
  • #37
chetzread said:
is there anything to do with the metacentric height , buoyant point in this question ?
Not specifically. I just wanted to alert you to the fact that the topic is subtler than may appear, that it might not actually be true that the object would always be more stable in the lighter fluid, and that even if it is a rigorous proof would not be easy.
 

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