Buoyancy Calculator

Table of contents:
This calculator lets you determine the buoyant force of liquids. Given a liquid's density and the volume of an object in that liquid, the calculator will output the amount of force keeping the object afloat. The calculator allows for input of fluid density and object volume and outputs the buoyant force and the weight of the displaced fluid.

If you don't happen to know the fluid density expressed in mass over volume, the calculator has several presets to use for water, sea water, ethanol, methanol, fuel oil, heating oil, automotive gasoline, and sulfuric acid. Advanced mode also allows you to tweak the gravity setting, in case you're measuring buoyancy somewhere besides the Earth's surface.

For the record, mercury is the densest liquid, being a liquefied metal at room temperature after all. A British one-pound coin will easily float on the surface of a container of mercury, due to a combination of buoyant force and surface tension. Do account for surface tension in real-world applications of this calculator.

Buoyancy Explained

Buoyancy is simply the action of gravity on liquids, giving them a resistant force against having other objects submerged in them.

Buoyancy works against the weight of the submerged object, in proportion to the volume of liquid that object would be displacing. The exact same laws of physics explain why a helium balloon floats in Earth's atmosphere, helium being lighter than air and held up by atmospheric buoyancy.


To use the calculator, figure these factors:

	p - The liquid's density, expressed as kg/m^3 (kilograms divided by (meters cubed)).
	V - The volume of displaced liquid, measured in cubed meters.
	g - The gravity force in the subject liquid's region.
	B - The force of buoyancy.

By default, the calculator measures buoyancy on Earth at normal gravity.

Applications of Buoyancy

An understanding of buoyancy is necessary to work with just about any kind of liquid in large volumes. In the first place, it's essential knowledge in shipping, diving, and other aquatic activities.

One application of buoyancy familiar in our culture is the bartender's trick of serving layers drinks - several liquids of different densities in one glass giving it a striped appearance when viewed from the side. For instance, a B-52 cocktail has coffee liquor under Irish cream under Grand Marnier, three different liquids staying neatly in place because of different levels of buoyancy.

Buoyancy is also important in many engineering applications, especially when handling industrial liquids and gasses. Should an accident and necessary cleanup happen, it's good to know what you'll float or sink in!

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