2007-12-04 21:51:43 · 10 answers · asked by Katrina Danielle N 1 in Cars & Transportation ➔ Boats & Boating
Here is a simple way to demonstrate for yourself.
Take a peice of aluminum foil, wad it in a ball, it will sink like a rock.
Now form it into a boat shape or rounded over the bottom of a bowl, it will float.
The shape of the boat's bottom (or hull) spreads whe weight over a large area so the water can hold it up.
2007-12-04 23:57:27 · answer #1 · answered by Anonymous · 0⤊ 0⤋
A big heavy boat doesn't sink because it is designed to have a shape that will give it lots of 'buoyancy'. SHAPE is what results in buoyancy, and like weight, buoyancy is a 'force'. Weight is a downward force and buoyancy is an upward force.
If upward forces = downward forces, then it floats!
Upward force is buoyancy - caused by the pressure of the medium (water, say) to want to return to where it started (level) before it was displaced by the object, eg: a ship. The denser this medium, the greater the pressure and hence the greater the buoyancy (vessels float higher in salt water than in fresh because it is more dense).
Downward force is the weight of the vessel - caused by its mass x acceleration due to gravity.
The point at which these two forces equalize or become stable, is the point at which the object floats. (Where upward forces = downward forces). If they don't equalize, then the object sinks - but the upward forces are still acting on the submerged object, so under the surface of the medium it's weight is less than when is was above the surface. (Though it's mass is still the same).
[Note: it doesn't really have anything to do with "air" inside the object. It is simply the weight (the downward force). Clearly a solid block of tin that is the size of a biscuit tin would sink, whereas the biscuit tin would not, this is not because of the air inside the tin - it works even if you take the lid off or the air out! - it is because the solid tin would weigh thousands of times more than the normal biscuit tin. The upward forces (the buoyancy) are THE SAME on each object - because they are the same shape. But the downward forces are not.
Because the biscuit tin is very much LIGHTER than the solid block, the upward force would very quickly be equal to its weight - at which point it would float. But the (same) upward force would be nowhere near equal to the weight of the solid block - so it would not float.
Don't forget: buoyancy is the upward force, weight is the downward force. And they are both in kilograms. If there is 10 kg of buoyancy and 2 kg of weight, then it floats - mostly OUT OF the water. If there is 10 kg of buoyancy and 8 kg of weight, then it floats - mostly IN the water. And if there is 10 kg of buoyancy and 12 kg of weight, then it SINKS.]
2007-12-06 13:18:07 · answer #2 · answered by Girly Brains 6 · 2⤊ 0⤋
It's like a 5 Gallon bucket it takes a lot of down pressure to push it down>But if you tilt it water come in and fills it up then sinks>
Called bouncy>>
2007-12-05 09:12:31 · answer #3 · answered by 45 auto 7 · 0⤊ 0⤋
in addition to the magic of bouyancy think of it this way.
Take a million pound chunk of Styrofoam. It weighs a million pounds, but it floats. How come? Because it is less dense than water.
Gasoline floats on water. Why? Because it's less dense than water. Ice floats on water. All it is is solid water so why does it float. Because it's got air trapped inside and so it averages less dense than the water it was before it froze....
Now take your million pound chunk of steel. Shape in into a boat that floats. That shape has lots and lots of air inside of it, right? AVERAGE the density of steel with the density of air and you get something that is less than the density of water so it floats.
Let in water that displaces the air and eventually you get to an average greater than 1 ( the density of water) , and down you go.
2007-12-06 07:33:21 · answer #4 · answered by yankee_sailor 7 · 0⤊ 0⤋
say you have a block of iron, 1 foot square. heavy, right? now take that block of iron and pave it out flat to 100 feet by 100 feet. now cut out a 1 foot square of the paved iron, light right. That's what the water sees.
2007-12-05 06:08:39 · answer #5 · answered by 1000 Man Embassy 5 · 0⤊ 1⤋
Because it weighs more than the water it displaces. There for it is heavier than the water and it sinks to the bottom like a rock.
2007-12-05 05:56:23 · answer #6 · answered by big.boy802 2 · 0⤊ 3⤋
Look up Archimedes principle, or buoyancy and get a good explanation.
2007-12-05 07:28:15 · answer #7 · answered by landfall43 4 · 0⤊ 0⤋
the shape of the hull and it displaces more water than it weighs therfor it wont sink.
2007-12-05 10:01:27 · answer #8 · answered by Anonymous · 0⤊ 1⤋
Magic!
http://www.ajax4hire.com/M_Media/Misc_Mickey_Mouse_as_Wizard.gif
The Bouncy theory works better. But, it was already mentioned.
2007-12-05 10:05:00 · answer #9 · answered by Snaglefritz 7 · 0⤊ 1⤋
Please use Yahoo! answers search. This question is very popular, and i'm sure you'll find everything you need.
Tip: try to search for displacement.
2007-12-05 09:41:02 · answer #10 · answered by Damon_ru 3 · 0⤊ 0⤋