2006-06-23 23:15:44 · 12 answers · asked by annie 2 in Science & Mathematics ➔ Physics
In physics, buoyancy is an upward force on an object immersed in a fluid (i.e. a liquid or a gas), enabling it to float or at least to appear lighter
It was the ancient Greek, Archimedes of Syracuse, who first discovered the law of buoyancy, sometimes called Archimedes's principle:
The buoyant force is equal to the weight of the displaced fluid.
If the weight of an object is less than the weight of the fluid the object would displace if it was fully submerged, then the object is less dense than the fluid and it floats at a level so it displaces the same weight of fluid as the weight of the object.
An object made of a material of higher density than the fluid, for example a metal object in water, can still float if it has a suitable shape (e.g. a hollow which is open upwards or downwards) that keeps a large enough volume of air below the surface level of the fluid. In that case, for the average density mentioned above, the air is included also, which may reduce this density to less than that of the fluid.
2006-06-24 00:07:14 · answer #1 · answered by piyush s 1 · 0⤊ 0⤋
Usually we can expect a question like, ' how some bodies like wood etc. float in liquid?'
The answer is it is gravitational pull of earth; which we call as weight.
Just like air, water also exhibits an upward force. But the weight of metals and stones are greater than the upward force. Hence, the stone or metal sink in water.
2006-06-23 23:31:15 · answer #2 · answered by Pearlsawme 7 · 0⤊ 0⤋
metals and stones don't always sink in water - if they did we wouldn't have ships.
something floats if its mass is less than the mass of the water that has had to be moved out of the way
2006-06-23 23:22:44 · answer #3 · answered by Ivanhoe Fats 6 · 0⤊ 0⤋
Its because stones and metal have higher density than water... that's why its sink...
Also why does a stone sink and a ship floats because of bouncy-Archimedes principle
2006-06-23 23:50:03 · answer #4 · answered by sauron s 2 · 0⤊ 0⤋
Because there is either no locked air in them or if there is, there is not enough to bring the weight of the rock or metal of the object to the surface of the water, unless it is volcanic rock pumace.
2006-06-24 06:42:01 · answer #5 · answered by Some Chick 5 · 0⤊ 0⤋
Metal boats don't sink.
Even if they have stones in them.
2006-06-23 23:19:12 · answer #6 · answered by Epidavros 4 · 0⤊ 0⤋
They are more dense than water
2006-06-23 23:17:37 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Bodies float again dont they??
2006-06-23 23:20:51 · answer #8 · answered by Ron~N 5 · 0⤊ 0⤋
its because those materials are more dense than water!!!
2006-06-23 23:32:41 · answer #9 · answered by Anonymous · 0⤊ 0⤋
buoyant is less compared to there weight
2006-06-23 23:18:17 · answer #10 · answered by nothing special 3 · 0⤊ 0⤋