why does a ship float in water while a needle sink in water?

Answer 1

Tensile energy.

Answer 2

To understand what makes a heavy steel ship float, you have to think
of “floating” as the point at which an object stops “sinking”. An
object floats on water because it displaces – or takes the place of –
the amount of water equal to it’s own weight. The more water the ship
displaces the more “boyant”, or floatable, it becomes. A ship (or
anything else that floats) sinks into the water until it has displaced
its own weight of water, then it will not sink any further. If a ship
weighing 100 tons is placed in the water, it will move aside up to,
but no more than 100 tons of water. Because a ship is a lot like an
empty bowl – relatively thin steel on the outside and nothing but air
on the inside – its actual density is less than that of the water it
displaces. So, a 100 ton ship will not displace so much water that it
goes down into the water below the sides of the boat. This causes the
ship to float on the water. This explains why a solid block of steel
will sink and a hollow bowl of steel that weighs the same will not.

Answer 3

Look at the surface area that is touching the water in each case. A needle has a long, extremely thin area, whereas a ship has a huge amount. If you were to put a needle on a piece of foil, it would 'float' again because the surface area that is spread across the water is supported more.

Answer 4

Displacement. A wider area covered, the better something will float. A boat has a much larger area covered, while a needle has a tiny strip, so the boat will float, you hope, and the needle sink.

Also, density. A ship is mostly hollow, while a needle is densely packed over a smaller area.

Answer 5

The ship is hollow, so it weight is spread over a large area of the water surface. This makes the ship's bow weigh less then the amount of water it displaces, so it floats. The needle is not hollow, so it weighs more then the amount of water it displaces, so it sinks.

Answer 6

Density.
Anything less dense than water (density = 1) will float on water. Anything more dense than water will sink. It's interesting that when water freezes, it actually becomes less dense. That's why ice floats in water. The most dense liquid is mercury. You can float a brick in a puddle of mercury.

Answer 7

It's all about density. The denser a material, the more likely to sink. However, it is the density of the entire object that counts. A boat contains alot of air, so that the overall density is less than that of a needle. That's why, when the Titanic's air filled chambers were torn apart, it sunk. Water flowed in, and increased the overall density.

Answer 8

Like a bottle of air will float but a bottle of water will sink. The air is lighter and prevents the heavier container material from sinking. Not very technical...

Answer 9

It is all about displacement. The hull of a ship is supported by the pressure exerted against the hull by the water that is being displaced by the ship. The basic shape of the hull of the ship helps with this also. For this reason a sheet of metal wont float either :)

Answer 10

a log has more surface area than a needle. if you try really carefully, you can get a needle to float on water. Try filling a glass all the way to the top, so you get the "curve" and then put the needle on. It works!!

Answer 11

weight and water displacement. any thing that weigh less than the amount of water it displaces will float