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Weird Science: Archimedes principle

The U.S. Navy Nimitz class aircraft carriers are one of the largest ships (SF Fig. 2.5). A Nimitz class carrier is over 75 m at its widest point and is over 325 m long. A Nimitz class carrier turned up on its stern (back), it would be taller than the Eiffel tower!  Even more impressive is that a Nimitz class carrier weighs about 99,000 metric tons (99,000,000 kg)!  How does such a colossal and extremely heavy ship float?

 

SF Fig. 2.5. An aircraft carrier floating.
 
Objects are able to float in water if they are buoyant. The Greek philosopher Archimedes first explained buoyancy. Archimedes noticed that the water level of his bathtub rose as he submerged himself in the water. From this observation he realized that water exerts a force, called a buoyant force, which is equal to the weight of the water that the object displaces. This is known as Archimedes Principle. 
 
Archimedes Principle says that if an object is less dense than water, then it will experience a buoyant force great enough to make it float. This is why a 99,000 metric ton Nimitz class aircraft carrier is able to float. The carrier has lots of rooms and compartments within its hull that are full of air.  All of the empty space inside of the ship makes the ship less dense then the surrounding water and so it is able to float!
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.