Understanding Buoyancy: The Role of Object Shape and Archimedes' Principle

[mreccentric]

I had read that, according to Law of Buoyancy/Archimedes Principle,
"Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object."

But does that depend on the shape of the object immersed? I see, that a metal block doesn't float when it's immersed in water. Please help me understanding this.

 

[Doc Al]

But does that depend on the shape of the object immersed?

No, just on the volume of fluid displaced.

I see, that a metal block doesn't float when it's immersed in water.

Whether an object floats or not depends on how the buoyant force compares to the weight of the object. If the buoyant force is enough to counter the weight of the object, then it will float.

If you submerge two identically shaped and sized blocks under water, the upward buoyant force on each is the same even though one might be wood and the other metal.

 

[Buckleymanor]

Whether an object floats or not depends on how the buoyant force compares to the weight of the object. If the buoyant force is enough to counter the weight of the object, then it will float.

It's compared to it's density not it's weight.

 

[Doc Al]

It's compared to it's density not it's weight.

No, the buoyant force must be compared to the weight of the object.

You could express the condition for floating in terms of density: If the density of the object is less than the density of the fluid, then it will float. Which is a perfectly fine way to look at it. (Equivalent, of course.)

 

[russ_watters]

Using density can be confusing for objects of nonuniform density, like ships.

 

[Buckleymanor]

What's confusing about it if you just consider the overall density.Weight is where I get confused a ship weighing 10 ton floats a ten ton block of steel sinks.

 

[Buckleymanor]

You could express the condition for floating in terms of density: If the density of the object is less than the density of the fluid, then it will float. Which is a perfectly fine way to look at it. (Equivalent, of course.)

Yes, which was what I was trying to say but without explaining the buoyant force.If the overall density of the object is less than the fluid it is submerged in then the object floats if it's more it sinks.
If the object floats the amount of fluid it displaces is equivalent to it's own weight.