What's density? ????

Answer 1

All the techncal answers here are correct, density refers to the amount of matter which is found in a given amount of space. Think of it in terms of people on a subway car, the people standing in for atoms. A subway car has a given amount of space that people can fill. At some times of the day, you will find the car holds one or two people, at other times it may hold a dozen or so. At peak hours, that same car is jammed with people. If you counted the number of people, that would tell you the density. Now density is affected by a few things, first being the size of the atom or molecule you are trying to pack into your given space. In our case, the subway car. Obviously, you could fit in a lot more runway models than you could sumo wrestlers into that same car. So the size of the thing affects the final density. Temperarture also counts. Atoms and molecules are always in motion, and heat speeds up that motion. On the flip side, cold tends to slow them down. When it's hot, molecules don't like to be very close to one another- just like when the temperature in the summer climbs towards 100, you don't feel like rubbing elbows with a bunch of folks in the subway car. Everyone wants space so they don't feel sticky and have some air to breathe. Now when it's winter, it feels much warmer to be jammed into that same car with lots of other folks, because you can share what heat there is and stay warmer. Atoms tend to like doing the same thing.
All matter has a particular state it seems to prefer, especially at what we call room temperature. In some cases, it's a solid form, and the molecules and atoms are tightly packed together,like the top of your desk. The molecules which make up the wood are packed together fairly closely, in other words, they have a higher density than something not in a solid form. Like the water or soda you drink. Those molecules are not so tightly packed together, and that's what gives liquid it's peculiar qualities, like being able to spill or take on the shape of the container. Some other things prefer a lot of space, like the air you breathe. Air is less dense than coke, even in the same amount of space, at room temperature. That's because the molecules which make up air think room temperature is still way too hot for their liking. It takes a lot of cold to force gas elements and molecules to take on a liquid state.
Which brings us to the last thing that can affect density- which is pressure. Think of pressure as squeezing in those molecules, forcing them into a small space. Sort of like when the subway car is just jam packed with people, and one more person manages to force their way in the door. Everyone else has to shift, suck it in, and generally have a miserable ride to the next stop. We can force molecules and atoms into a space, even to change from a gas to a liquid, or at least squeeze into a liquid, by increasing the pressure on them, while maintaining the same temperature. That's how they keep the fizz in your soda. The liquid and gas- the carbon dioxide bubbles- get forced into that can under pressure. As long as the can is strong enough to contain the stuff, at room temperature you can convince them to get into the can together. When you pop the top, you release the pressure, the gas can now get out, and you have a nice fizzy drink- at least until all the gas escapes and you are left with flat Coke. The liquid won't go anywhere, because at room temperature, it's naturally a liquid. Without the gas stuffed in the can with it, it returns to the original density it had before they stuffed in all the gas.
So density is an amount of "stuff" packed in a given space. Density is why ice floats, Coke bubbles, and subway riders get irritable at peak hours. It is affected by size of the molecule or "stuff" being packed into the space, by temperature, and by pressure. The density of something also determines the form it will take at any given temperature, and what form it prefers to take, whether that is a solid, liquid or a gas. Hope this clarifies things for you some.

Answer 2

Density, or volumic mass (ISO 31), is a measure of mass per volume. The average density of an object equals its total mass divided by its total volume. An object made from a comparatively dense material (such as iron) will have more mass than an equal-sized object made from some less dense substance (such as aluminium).

Answer 3

Density is the amount of mass per unit volume.
The average density of an object equals its total mass divided by its total volume. An object made from a comparatively dense material (such as iron) will have more mass than an equal-sized object made from some less dense substance (such as aluminium).

Answer 4

density is the amount of mass per unit of volume and has units such as g/cc or lbs/in^3. Sometimes Specific gravity is mistaken for density but it is not. Specific gravity is a ratio of the density of an object over the density of water and hence has no units.

Answer 5

The amount of matter contained within a given volume.

Answer 6

It is the number of molecules in a given area. Like for example black holes are very dense. Lead is very dense. Whip cream is very light, not dense.

Dense is like thickness in fog, a light fog or a dense fog.
Dense is heavier, more crowded, more packed, more gravity.

Hope this helps!

Answer 7

density=mass of a substance/volume of the same substance
(mass=amount of matter contained in it .S.i unit is KG)
(volume=amount of space ocuppied by that substance.S.i unit is
m^3)
i learned this when i was 4yrs old.

Answer 8

oh!
its simply mass/volume.......its often said that its the heaviness of the substance.........

Answer 9

physics.about.com/od/fluidmechanics/f/density.htm