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Why can ships float?

PHYSICAL WORLD: Students from Aquinas College asked this question

The answer to why ships can float comes from the famous principle of Archimedes which says that the net upward force on an object immersed in water is equal to the weight of the water displaced by the object. If a large object like a ship is lowered slowly into water, it will displace more and more water until the weight of water displaced equals the weight of the ship, at which point it will stop dropping and “float”. If, of course, the ship is too heavy (say it was filled with too much steel or other heavy stuff) then the weight of water displaced will never equal the ship’s weight and it will never float (it will sink like a stone).

Our expert

Professor John Harvey anwered this question. He is a Fellow of Royal Society Te Apārangi, which means he’s one of the top experts in his field of photonics and optics. John started the University of Auckland Laser Lab in the early 80′s and has been CEO of Southern Photonics since its inception in 2001.

For more information visit:  http://www.southernphotonics.com/about-us/prof-john-harvey/