One of the core skills we use as scuba divers is controlling our buoyancy. That is controlling where we are in the water column.
When we’re in the water we have two forces acting on us. The balance between these two forces determines where an object floats in the water column:
Force One) Weight. The weight of an object is the force down.
Force Two) Buoyant Force. The Buoyant Force is the weight of the water displaced by the object. This force pushes up
If the Buoyant force is more than the weight the object will be positively buoyant (it will float).
If these two forces are equal then the object won’t rise or fall…it will be neutrally buoyant.
If the Weight is more than the Buoyant Force the object will be negatively buoyant (it will sink).
One way to conceptualize the forces acting on us when we’re in the water is explained with Archimedes’ Principle.
Between one of these three you should get it down pat.
Here is a link to a more eloquent and academic explanation of Archimedes’ Principle.
The real story behind Archimedes’ Eureka! – Armand D’Angour
View full lesson: http://ed.ted.com/lessons/the-real-story-behind-archimedes-eureka-armand-d-angour When you think of Archimedes’ Eureka moment, you probably imagine a man in a bathtub, right? As it turns out, there’s much more to the story. Armand D’Angour tells the story of Archimedes’ biggest assignment — an enormous floating palace commissioned by a king — that helped him find Eureka.
The guys over at Team Life Guard Systems posted a link to an illustrated story of Archimedes’ Principle.