I Wonder Why
For the longest time I had wondered why a small piece of metal sinks when thrown in water while a big ship stays afloat.
Eureka! Eureka! Do these words ring a bell? Yes, these were the words shouted out by Archimedes as he discovered displacement and buoyancy: the principle behind the floating of a ship.
Buoyancy is the force which a liquid exerts on an object which is partially or fully immersed in it. This force is always upwards. The weight exerted by the ship is due to the pull of gravity and it acts downwards. Hence these two forces are in opposite direction so tend to cancel each other.
As a ship enters the ocean it displaces water. To ensure that the ship does not submerge, the amount of water displaced by it should be the same or more than the weight of the ship. A special formula devised according to the Archimedes principle helps engineers design the weight and dimensions of the ship, to help it stay afloat. Did you know the average weight of a big cruise ship is 71.500 tons before the people and cargo are added?
This is the principle on which a ship and many other large things float. Can you now find out where else the Archimedes principle is used? I can give you a clue; it is for something that does not float on water!
