# Sink or float, high density low pressure VS low density high pressure

• Albertgauss
In summary, under normal conditions, an object with a higher density will sink in a fluid with a lower density. However, if the pressure increases to a high level, then the object's density can increase and it can start to float.

#### Albertgauss

Gold Member
Normally, an object with a high density will sink in a fluid with low density. What if, as depth increases, as in the case of the ocean, the pressure really gets cranked up -> Is it possible for a low-density, high-pressure fluid to float a high-density object, that, under normal conditions would sink in the low-density fluid?

The ocean is a perfect example. Though its density doesn't change much with depth, its pressure gets huge by the time you get to the bottom of the seafloor. At the the surface of the ocean, anything with more density than seawater sinks, but could such an increase in pressure cause a normally sinking object to float in deep ocean depths before it hits the sea floor? Can high pressure, alone, cause things to float? Or will, density always rule, no matter the pressure, in determining whether an object sinks or floats in any medium?

The pressure doesn't matter. It's whether or not the density of the liquid increases to the point that it surpasses the object.

Albertgauss said:
Normally, an object with a high density will sink in a fluid with low density. What if, as depth increases, as in the case of the ocean, the pressure really gets cranked up -> Is it possible for a low-density, high-pressure fluid to float a high-density object, that, under normal conditions would sink in the low-density fluid?

If anything, it's the other way around. Liquids don't generally compress, so the density of the fluid doesn't increase much with increasing depth and pressure, hence no increase in buoyancy with depth. However, the increase in pressure can compress the object, increasing its density and therefore making it more likely to sink.

For example: Most people, if their lungs are full of air, will float to the surface from a depth of three meters under water. At a depth of 100 meters, the higher pressure compresses the chest cavity and the lungs enough that the overall density becomes greater than that of water, and the human body sinks even with full lungs.

Density is the only important factor, sorry, it is definitely not possible to have dense objects float in less dense ones.

I got it everyone. Thanks for your help. I think I kind of knew, but one can always hope for surprises.

## What is the concept of "sink or float"?

The concept of "sink or float" refers to the behavior of objects when placed in a liquid. Depending on the density of the object compared to the density of the liquid, it will either sink or float.

## What is the relationship between high density and low pressure?

High density and low pressure are indirectly related. As the density of a material increases, the pressure required to compress it also increases. This is known as the bulk modulus of the material.

## How does low pressure affect the density of an object?

Low pressure can affect the density of an object in two ways. First, if the object is a gas, low pressure will cause it to expand and decrease in density. Second, if the object is a solid or liquid, low pressure will decrease the amount of force pushing down on the object, causing it to float more easily.

## What is the difference between low density and high pressure?

Low density and high pressure are also indirectly related. As the density of a material decreases, the pressure required to compress it also decreases. This is known as the compressibility of the material.

## How does the behavior of objects change when comparing high density low pressure and low density high pressure?

The behavior of objects will depend on the specific densities and pressures involved. Generally, high density low pressure objects will sink more easily in a liquid, while low density high pressure objects will float more easily. However, other factors such as surface tension and shape of the object can also play a role in determining whether an object will sink or float.