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How to Get an Object Denser Than Water to Float

Objects float because the liquid they're in is heavy enough to press against their sides and push the object up out of the water. An object that's more dense than the liquid it sits in sinks because it's heavy enough to push aside the volume it displaces. An object that's less dense floats. It's impossible to make an object float if it's more dense than the liquid it's in, but you can do certain things to alter the conditions and change the relative densities of the liquid and object.

Things You'll Need

Heating and cooling equipment
Salt
Vacuum pump

Instructions

- 1
  Dissolve something such as salt or sugar in the water. This increases the density of the water and makes it able to float more dense objects than before.
- 2
  Cool down the water. This fractionally increases its density while it's still above freezing. This also will cause more dense objects to float than before.
- 3
  Heat the object. This causes it to expand and lose density, and become more buoyant in water.
- 4
  Put a slightly porous object and the water in a vacuum chamber. Drawing the air out of the chamber causes the object to expand more than the water. This allows an object that was previously slightly negatively buoyant to float.
- 5
  Shape the object so that it traps enough air to become buoyant. The object can be extremely dense, but if it contains a large cavity of air, it will float. This is how ships made of metal are able to float.

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