Why do boats made of iron float

I liked it a lot. Thanks a lot!!!! Friday, February 24, Why does a ship made of iron float while a piece of iron of same mass sink in water? It has full of air filled in it. So the average density of the ship as a whole is less than the density of water.

Therefore immersed portion of the ship displaces water equal to its weight. So the ship floats whereas a sheet of iron is compact and there are no air spaces inside it. Iron is denser than that of water. The weight of the sheet is greater than the weight of the water displaced by the sheet. So it sinks. So it floats upon the water. Hence the ship does not sink. For the nail,. The density of nail as of iron is much larger than the water. So it sinks easily. Archimedes' principle states that.

The weight of the water displaced by the ship is equal to its weight, so it floats. Whereas the weight of the water displaced by the iron nail is less than its weight so the iron nail sinks. 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.

The next question to ask involves floating itself. How do the water molecules know when 1, pounds of them have gotten out of the way? It turns out that the actual act of floating has to do with pressure rather than weight. If you take a column of water 1 inch square and 1 foot tall, it weighs about 0. That means that a 1-foot-high column of water exerts 0. Similarly, a 1-meter-high column of water exerts 9, pascals Pa. When the aluminum ball had a diameter of 6.

And as long as the ship displaces enough water to create a strong buoyant force, it can stay afloat—even if it is loaded with cargo. As the diameter decreased and density increased, the ball should have sank more and more.

When its diameter was about 1. This is when the ball had a density approximately equal to that of water. With a diameter of about 1. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Key concepts Hydrodynamics Fluid dynamics Physics Water Introduction Have you ever wondered why when you drop a steel nail into water it sinks like a stone, but when a well-built steel ship is in the ocean it floats, even though it weighs much more than a tiny nail?

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