I know that the displacement of water needs to be equal to the weight of the object but then why do some objects, like an anchor, sink straight to the bottom regardless of how much water is present.
2007-03-05 02:46:00 · 12 answers · asked by moose 2 in Science & Mathematics ➔ Physics
The “the displacement of water needs to be equal to the weight of the object “ is only correct if the object actually floats. If the object sinks, the displacement of water is whatever volume the object occupies, and the weight of this volume of water will be less than the object that sinks. The volume of water the object is placed in, whether it be a bathtub, teacup, or ocean has nothing to do with it.
When something floats on water, part of its volume will be below the surface. For ships, this is called the draft. The draft displaces a volume of water that weighs exactly the same as the object that is floating, which is Archimedes’ Principle. As the load increases, so does the draft… right up to the point where water flows over the top and completely covers the object. At this point you have neutral buoyancy, assuming the water doesn’t enter the ship and add to the load. If you increase the load beyond the point of neutral buoyancy (say, by admitting water or placing a lead weight on the submerged object) the buoyancy will be negative and the object will sink, like an anchor.
At neutral buoyancy the volume of water displaced by a submerged object weighs exactly the same as the object. This is how submarines maintain their depth: they adjust their weight by admitting sea water into ballast tanks, or expelling sea water from the ballast tanks with compressed air, until neutral buoyancy is achieved.
As others have said, it’s all about volume density: weight per unit volume. If we arbitrarily take the volume density of water to be unity, than anything with volume density less than unity will float, anything with volume density more than unity will sink.
2007-03-05 03:45:58 · answer #1 · answered by hevans1944 5 · 1⤊ 0⤋
The part you are misunderstaning is 'displacement of water', which is another term for volume. Basically, if density (weight/volume) is less than that of water (1kg/l), the object floats, if it is greater, it sinks.
You are not measuring the amount of water in the tub, ocean, or whatever--you are measuring the amount of water that will rise if you submerged the object. Archemedies discovered the idea by jumping into a full-to-the-rim bath tub and seeing it overflow. The volume of water that flowed out is the same as the volume of his body.
2007-03-05 02:53:47 · answer #2 · answered by wayfaroutthere 7 · 0⤊ 0⤋
an object can only displace as much water as it has volume. Once it has fully submerged if the weight of the displaced water is still less than the weight of the object then it will continue to sink.
2007-03-05 02:53:18 · answer #3 · answered by Anonymous · 1⤊ 0⤋
anchor yu said is to make ship tied or stable. also u mentioned that the displacement of water needs to equal to the weight of the object. But hellllllllllllllllllllllllllllllllllow yu sink anchor in waters of ocean, sea and not in some bath tub ok.
2007-03-05 02:58:15 · answer #4 · answered by Anonymous · 0⤊ 1⤋
It has to do with the contrast in density. Objects that are more dense than water (an anchor) sink. Objects that are less dense than water (Styrofoam) will float.
2007-03-05 02:52:27 · answer #5 · answered by smellyfoot ™ 7 · 2⤊ 0⤋
Displacement deals with both weight and volume.
A Balloon weighs very little for the space it takes up, fill it with lead and now it weighs more then the water it will displace for the space - Volume - density that it occupies.
2007-03-05 02:51:58 · answer #6 · answered by occluderx 4 · 0⤊ 0⤋
Difference in density.
Your anchor as an example: Iron density is about 7,000 kg/m³ whereas water density is 1,000 kg/m³... It sinks in water.
The other side of the question: An oil density may be around 850kg/m³... it floats on water.
2007-03-05 03:35:34 · answer #7 · answered by Norrie 7 · 0⤊ 0⤋
its gotta do with the difference in density between the water and the object. If the object is denser than the water, it will sink and vice versa
2007-03-05 02:50:45 · answer #8 · answered by Anonymous · 0⤊ 0⤋
It's all about density. If an object weighs more then water per cubic centimeter (or whatever cubic unit you want to use), it will sink, if it weighs less it will float.
2007-03-05 02:51:52 · answer #9 · answered by Roman Soldier 5 · 0⤊ 0⤋
Well: according to some are" Lighter than others because
by telling how much each one does work differently by Balanced
weights "
2007-03-05 03:03:10 · answer #10 · answered by toddk57@sbcglobal.net 6 · 0⤊ 0⤋