Why a stainless steel boat can float while a neddle sinks?

Question

Why a stainless steel boat can float while a neddle sinks?

Answer 1

A neadle will float on water if you do not let the piont of the needle penetrate the surface of the water.This requires a steady hand and forebearance.I did this experiment many times several years ago.It follows that it would be difficult to attempt to float a needle on water that ripples.Finally,it must be remembered,that steel boats are designed to float,whereas,needles are not,but nonetheless,are needle can be floated on water.Try floating a needle in a saucer or bowl of water!

Answer 2

same way concrete  sailboats float,  water displacement

Answer 3

Displacement--simple physics of water supporting the weight by displacing the water around the boat. A needle just doesn't displace any water

Answer 4

A needle can float. Take a glass of water, place a small peace of tissue paper on the surface and lay the needle on it. When the tissue sinks from being water lodged, the needle will float, due to surface tention on the needle.

Answer 5

A boat floats because it can displace water weighing more than it does.  A needle cannot.

The other guy described a needle floating via surface tension, which is too weak to be of much concern when considering keeping a stationary boat afloat.  It is not the same as buoyancy.

http://en.wikipedia.org/wiki/Bouyancy

Basically, a boat floats for the same reason that a balloon does, or why hot air rises.  It's because it weighs less than something taking up the same volume.  Therefore everything that is more dense than it is has more force acting on it in a smaller space, meaning it is pulled downward more strongly...which in a fluid means it will flow underneath the lighter object, and the lighter object will rise until it gets to a point where it is no longer lighter than the surrounding medium.  (In the case of water, generally the surface.  In the case of air....whereever the density of the air is the same as the density of the inside of the balloon or hot air mass)

I hope that made sense.

A metal boat is a thin sheet of metal with a lot of hollow space inside.  If you were to fill that space completely with water, it would weigh many times what the steel of the boat is made of weighs.  

A needle has (generally) no space inside.  It is solid steel which is more dense than water.  Therefore it sinks.

Answer 6

displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place, so that it can be weighed.

An object that sinks also displaces an amount of fluid equal to the object's volume. Thus buoyancy is expressed by Archimedes' Principle which states that when this happens, the weight of the object is reduced by its volume times the density of the fluid. If the weight of the object is less than this quantity, it will float, if more it will sink. The amount of fluid displaced is directly related (via Archimedes' Principle) to its weight.

Displacement is used as a measure of the weight of ships (see: Hull (watercraft), load line and Stability conditions (watercraft). The displacement of a vessel is equal to the weight of water it displaces when afloat.

Vessels such as naval ships and icebreakers are often measured by their displacements. The unit of measure can be long tons or metric tons depending on the country of origin. The ship can be measured in light condition, fully loaded, or normal (usually fully loaded, but with about two-thirds of fuel and unconsumables). For official purposes, the Washington Naval Treaty introduced the standard displacement, which was the displacement fully loaded but with no fuel or reserve feed water.