the density of the mass is greater or less than that of the water
2006-10-16 05:48:32
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answer #1
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answered by akelaamy 5
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When an object is suspended in a liquid, such as water, it pushes down on the water with a force equal to its weight. This causes some of the water to move out of the way, or be displaced. The water then pushes back against the object with a force equal to the weight of the water than was displaced. This is the buoyancy force. If the density of the object is greater than that of water, the buoyancy will not be able to completely cancel the weight and it will sink. If it is less, it will float. If it is the same, it will stay wherever you put it in the water and will not float or sink.
2006-10-16 05:58:33
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answer #2
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answered by stormfront105 2
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Short answer is "density."
If the object is more dense thant water, it will sink. If less, it will float. Density is another way of saying how close packed the molecules of an object are.
Some people confuse "weight" with density. This is not exactly correct. An aircraft carrier weighs many tons. The material, steel is MUCH denser than water. The difference is that the ship is a large "bowl", full of air. The air in the ship, which is very much less dense than the water, Allow the ship to float.
So, the combination of the steel and air, which make up the ENTIRE ship, is less dense than the water on which it floats.
If you want to learn more about how heavy things like ships can float, look up the word "displacement," and do a search about an ancient Greek scientist named, Archimedes. He used different words than I, but he discovered those things in his bathtub.
There is a type of stone that floats in water. When a volcano shoots molten rock into the air, during an eruption, sometimes it mixes with the air, forming many tiny bubbles, trapped in the rock as it cools. This stone, called "pumice" is like a hard "foam." There is enough air, trapped inside to let the rock float. This volcanic stone is still rock, just as heavy as any rock, but the density of the entire piece of pumice is less than water.
2006-10-16 05:52:34
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answer #3
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answered by Vince M 7
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If the Volume of the Object is greater than the weight of the object and the Surface Tension which is exerted by the water,it will float.
For example; A piece of wood is light in weight but larger in volume and can balance the S.F,It floats.
A steel pin is very small,and has not such volume
to balance the S.T.,it will immersed.
2006-10-16 06:06:20
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answer #4
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answered by k.k s 2
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If the density of the mass is greater than the water, it sinks. But if it's less than the water's density, float.
2006-10-16 09:54:12
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answer #5
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answered by Belphegore 5
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an object sfloats in water because its density is less than 1 g/ml, an object sinks in water if the density is more than 1 g/ml
waters density is 1 g/ml
to find density use thos formula mass/volume
2006-10-16 06:08:43
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answer #6
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answered by derek6711 3
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If an object's mass is more dense, it's molecules are more tightly packed and it will sink, if it is dense enough to break the water's surface tension. If the objects' molecules are more loosely packed it will not break the water's surface tension, so it'll float.
2006-10-16 05:59:55
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answer #7
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answered by Hootcoot 2
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Density. Steel sinks in water because the water isnt dense enough to displace the weight of the steel. However, steel will float in Mercury because the mercury is more dense than the steel.
The density is directly related to boyancy. If a boat cant displace its own weight, it will sink.
2006-10-16 05:48:54
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answer #8
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answered by Steven 2
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"Buoyancy is the tendency of an object to float in a fluid. Buoyancy is controlled by differences in density between the object and the fluid.
For example, if you have a block of ice with a density of 0.91 g/cm3, and float it in water with a density of 1.0 g/cm3, the ice will sink into the water until 91% of its mass is submerged. " [See source.]
Fluids transmit pressure, in the case of open area water, pressure comes from its own weight and from the atmosphere pushing down on the surface of the water. These pressures acting on the area of an immersed body result in the force known as buoyancy. B = PupAup; where bouyancy is the net pressure Pup in the upward direction (toward the surface) acting on the area Aup parallel to the surface.
As a body is immersed in the water, it is met with more and more pressure because pressure increases with depth. This results because more water overhead means more weight.
At some point the body will be totally immersed and there will be water pushing down on it as well as pushing up through buoyancy. Unless the body is very big (tall), the sinking (S = PdownAdown) and buoyancy forces from water will be almost the same, but acting in opposite directions: up and down.
They will pretty much cancel out because Pup = Pdown and Aup = A down. This is the case when we immerse a paper cup, for example, so that it fills with water and the pressures from water on the inside and outside bottom are almost exactly the same.
Horizontal forces from water pressure cancel each other out. In which case the only net force acting on the totally immersed body is its weight (W = mg). And weight pulls downward; so the body will sink.
And, as we all know, a water filled paper cup will in fact sink. That results because the sinking and buoyancy forces from water are canceled out, leaving only the weight of the cup itself to pull it downward.
So why does an empty cup float? That's because the weight of the cup (W = mg) is directly offset by the buoyancy (B = PupAup). There is no offseting sinking force (S) because there is no water in the cup.
The same can be said for the ice cube we started with. It's weight, which is its volume times its density, is less than the water pressure pushing upward on its cross sectional area. And the water pressure depends in part on the density of the water as well as other factors, like salinity and temperature.
At the same depths, Pup in saltwater (saline) is greater than Pup in freshwater. This results because the density of satlwater is greater than that of fresh. So the weight of saltware and consequently its pressure is greater for saltwater than for fresh water at the same depth.
As a result, both the ice cube and the cup will float higher out of salt water than fresh water. This results because we reach B = W at shallower depths in saltwater when compared to feshwater depths for the same B = W effect.
So the bottom line answer is:
A body sinks when its weight exceeds the net buoyancy force; it floats when its weight is equal to that force.
2006-10-16 07:00:31
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answer #9
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answered by oldprof 7
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If an object can push out of its way (displace) more water than it weighs, then it will float. Otherwise, it must sink.
2006-10-16 05:57:00
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answer #10
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answered by Anonymous
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waters density is one g/cm3 above 1 g/cm3 sinks below 1 g/cm3 floats and i think if it is so close to one its called suspended where its in the middle the simple answer is that the density of water is one. thats the specific gravity of water. The actual density of water is one gram per milliliter. You can see that the specific heat of a substance is the same as its density without the units.
2016-03-28 11:42:47
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answer #11
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answered by Anonymous
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