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Why Ships Float
Density

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Density- ratio of mass of an object to its volume

basics1_wood.gif

Density is mass per unit of Volume.

  • A 'heavy' substance should really be described one which is of high density.

 

  • A 'light' substance should be described as having low density.

 

  • You can calculate the density of a substance by dividing the mass of a substance by the volume it occupies.

The Unsinkable Ship
titanic.jpg
~The Titanic~

It is not very hard to shape a boat in such a way that the weight of the boat has been displaced before the boat is completely underwater. The reason it is so easy is that a good portion of the interior of any boat is air (unlike a cube of steel, which is solid steel throughout). The average density of a boat -- the combination of the steel and the air -- is very light compared to the average density of water. So very little of the boat actually has to submerge into the water before it has displaced the weight of the boat.

Densities
 
if material is less dense than water: floats
if material is more dense than water: sinks
 
Water: 1gram/cubic centimeter
Ice: .917
Cork: .25
Alcohol: .8
Glass: 2.5
Air: .0001
Animal Skins: .86
Iron: 7.8
Wood densities vary....
 

The Different Densities of Wood...
basics2_pineoak.gif
Affect how they float.....

Wood Densities:
 
Birch: .705 grams per cubic centimeter
Mahogony: .705
Walnut: .593
Cherry: .433