2007-03-19 09:13:15 · 26 answers · asked by Khalil A 1 in Science & Mathematics ➔ Physics
An item will float if the amount of water it displaces is heaver than the item. A ship is shaped so that as it sinks, air is pushed below the water surface. (The interior of the ship is hollow). The air is less dense than water. The ship pushes water out of the way until the water it displaces weighs the same amount as the ship. The nail sinks because it is solid and more dense than water. It can't displace water enough to hold itself up.
In physics, buoyancy is the upward force on an object produced by the surrounding fluid (i.e., a liquid or a gas) in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object. The net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body. This force enables the object to float or at least to seem lighter. Buoyancy is important for many vehicles such as boats, ships, balloons, and airships.
2007-03-19 09:19:52 · answer #1 · answered by DanE 7 · 0⤊ 0⤋
Because the ship is hollow. It the density of material that determines whether it floats or not. If you take an iron nail, melt it down and make a large enough hollow ball out of it, it will float, since the total density becomes quite low (density = mass/volume).
However, if water can get inside of the ball, it will sink, since the density will suddenly go way up (water is much heavier than air). So if you poke a big hole in an iron ship, down it goes.
[The criterion for floating is when the density of the object is less than the density of the liquid it is immersed in.]
2007-03-19 09:20:16 · answer #2 · answered by Tom 3 · 0⤊ 0⤋
The iron ship has a mostly hollow interior. The interior is full of air. This means that the total density of the whole ship is the average of the volume of iron in the hull and the volume of air inside. This average density is less than the density of water, so the ship floats. There is no air in the iron nail- it is thus the density of iron alone, which is greater than the density of water. Hence it sinks.
2007-03-19 09:20:16 · answer #3 · answered by Ian I 4 · 0⤊ 0⤋
Because the iron ship displaces more water than it weighs, whereas the iron nail does not. The ship does this by the shape of its hull. If the ship were shaped like a big cube, it would sink like a rock.
2007-03-19 09:17:35 · answer #4 · answered by Anonymous · 2⤊ 0⤋
When a body is immersed in a liquid, it displaces some liquid equal to the volume of its immersed part. As Archimedes (Archi to his friends) who lived on this earth about 2300 years ago, found out and sprang out of his bath tub, wearing only his beard and nothing else, screaming: Eureka! Eureka! (meaning "I've found it! I've found it!" to you and me) that the immersed body (in Archi's case his water vessel, and himself) experiences a force, opposite to the direction of the gravitational force acting on the body and this force is equal in magnitude to the weight of the displaced liquid. Now, in your problem, the iron ship if it displaces (due to its shape) sea water which has a weight more than the actual weight of the ship, than it will float. Not only float but it will be able to carry some cargo until the total weight of the cargo plus the ship is just over the weight of the laden ship. Then it will sink. In the case of a nail, in your question, which is shaped like a nail (!) (i.e. not hollow like a ship) will displace water when it is immersed and experience a lift by the water. But the force in this case will be equal to the weight of the water equal to weight of the volume of water which is equal to the volume of the nail. As the unit volume of iron, which the nail is made of,
is heavier than the unit volume of sea water, the lifting force on the nail is less than the weight of the nail and, alas, the nail sinks. I hope this was helpful.
2007-03-20 04:00:33 · answer #5 · answered by East Ender 2 · 0⤊ 0⤋
a nail does not displace any water to gain floatation. a ship 'squashes' some water out of the way by being there, the water pushes back [up] against the ship and floats it!!
easy as 1, 2, eureka!!,
2007-03-19 09:25:50 · answer #6 · answered by billy bongo 2 · 0⤊ 0⤋
because the ship causes displacement in the water, holding an air pocket. The nail is not shaped to do this, thus sinks...
2007-03-19 09:18:25 · answer #7 · answered by xooxcable 5 · 0⤊ 0⤋
it has all to do with the surface area exposed: an iron nail has a very small sufrace area, while an iron ship has a much larger surface area.
same principle:
you have two A4 papers, you crush one and leave the other flat. you drop them at the same time from the same place. which of them reaches the ground faster? the crumpled one of course, it has a larger surface area on which air acts to break its fall!
good luck
2007-03-19 09:19:37 · answer #8 · answered by Vidya 6 · 0⤊ 0⤋
the shell of the ship displaces more water than the weight of the shell... archimedies principle
heat your nail up, beat it flat and create a "shell", it too will float..
pins float on water, and theyre Iron... but thats just surface tension...
2007-03-19 09:17:48 · answer #9 · answered by Anonymous · 0⤊ 0⤋
Its all about displacement my man. A concrete ship can float if it displaces enough water before sinking.
2007-03-19 09:21:19 · answer #10 · answered by the man 1 · 0⤊ 0⤋