I've always wondered how the titanic sank... well scratch that. I actually do know how and when? It involves an iceberg and water filling in the boat, therefore causing the boat to sink.
You've got the right idea, but to be more specific and more scien-ti-fic-E, what those people have witnessed is called buoyancy. The titanic was HUGE, yeah, but it had enough room for enough air to keep it afloat. UNTIL that iceberg came and it sank the ship (sad face). All this explains "density" and "buoyancy".
So you ask "WAHHHHHHHHH?" George Bush... Well let me explain to you and to others what density is. Well, density is the physical property of matter that can be found by dividing the matter's mass by its volume.
For example : A boat full of air is way less dense than a boat with water inside. Although water isn't all that dense, air molocules are less compact then water molocules. So now The Titanic makes since! Not only did it sink because the water weighted the boat down to the surface of the ocean, but also because it was way more dense with water then it was with air.
NEXT UP IS...
Buoyancy is the upward force that keeps thing afloat. For example, whenever we are in a pool or in water period we appear to float (kind of). Of course when you stop swimming you are somewhat sinking, but for the most part your being forced up to the surface of the water. But wait there's more! Buoyancy can't be buoyancy unless there's negative, positive, and neutral.
this is typically whenever a object floats.
this is typically whenever a object sinks.
this is when the object neither floats nor sinks.
So I think that's about it for Buoyancy, so now you may enjoy watching / listening to the following video and / or click the following links underneath.
wisegeek (talks about buoyancy and Archimedes) AND Density Chart of Different Materials AND BrainPOP wants to help !
