Random converter. Did you know that going paperless will probably not reduce the carbon footprint? Click or tap to find out why! Density indicates how much of the mass of a substance fits in a given volume.
Density varies for substances depending on their temperature and pressure. Higher pressure causes the molecules of the substance to become packed more densely within the same volume, increasing the density. Increase in temperature, on the other hand, generally causes the molecules to become more spaced out, thus decreasing the density. This is not always true, however.
For example, the density of ice is lower than that of water. When most other liquids solidify, the space between the molecules decreases. When water molecules freeze, the bonds within the molecules change intensity, and form a crystal. Space between molecules increases, volume of the water expands, and the density decreases.
Expanded volume of ice is why water that freezes in the house pipes in winter may make the pipes burst. When materials have higher density than that of water, they sink.
Conversely, materials with lower density float. A good example is ice floating in a glass of water. This property is often used in daily life.
In most cases hollow objects, made from more dense materials than water for structural reasons, contain air, which is less dense than water. This allows the vessel to float, as long as enough air is carried inside the cavity.
In fishing, the weight is made from high density materials such as metals, to make sure that it brings the hook down into the water, instead of having it float at the surface, especially when the bait is low in density and does not sink well. Oil is lower in density than water, so it floats. This property of oil allows for easier cleanups, when dealing with oil spills that frequently occur in the ocean and damage the marine ecosystem.
The tendency of oil and fat to float above water is also helpful when cooking — we can remove the fat that floats in our soup, for example, to reduce the percentage of fat and the calories in the dish.
This is especially easy if we refrigerate the soup until the fat solidifies. This is also easy to do on aspics. When making cocktails or other similar drinks, the ingredients can be chosen based on their density to create layers.
To make layers, a lower density liquid is poured slowly above the higher density ones. One can also use a glass stirrer as a guide for the liquid not for stirring. If done carefully, this technique will prevent mixing, and create a colorful layered drink.
It is also possible to do this when making jelly or aspics, although, if time permits, it is easier to refrigerate each layer separately and then pour the next layer on. In some cases, however, this quality may not be desirable. For example, when the substances containing fat do not mix well with water, they may separate, such as in a poorly blended smoothie, thus making the taste and the look of the food less desirable.
The density of the tomato is less than that of the salt water, but more than the density of the fresh water — this is why they are suspended in the middle. The density of water itself changes with the change of concentration of other substances mixed with water.
Water in nature is not always found in its pure H 2 O form, but is often mixed with other substances such as salt. Ocean water is a good example. For example, salt water in oceans has higher density than fresh water, which means that water with less salt in it floats in salt water. Of course it is difficult to see that with just water, but we can observe this property when we try to float in salt water.
We also have at least 5 percent of body mass consisting of fat. This data is for very lean athletes — the majority of us have at least 10 percent of fat but usually up to 20 in the majority of healthy individuals, and 25 percent or more in overweight and obese individuals.
When we try floating in salt water and then in clear water, we will notice the difference — our body will float easier in salt water. Even though people cannot sink below the water surface, caution must still be exercised when floating in the Dead Sea. Swallowing the water with such high content of salt causes a chemical burn that in severe cases has to be treated in the hospital.
Similar to water, objects that have lower density than air float. As the temperature of air rises, its density decreases. This is what makes air balloon rides possible. The hot air balloon in the archeological site of the ancient Mayan city of Teotihuacan in Mexico pictured is lifted up because the air inside it is heated above the temperature of the surrounding air, which, consequently, decreases the density inside the balloon envelope.
Sometimes, however, we might want to calculate the density by hand, especially if the calculations are not done under the standard conditions. To do this we can divide the mass by the volume, and we need to know these two values for the substance. We can measure the mass using a scale. The volume can be calculated based on the geometric shape of the object for simple solids, by using devices like a measuring cup or other measuring vessels for liquids and gases.
If the shape of the solid is too complex for the geometry-based calculations, we can find its volume using the volume displacement method.
We can do these calculations for objects of complex shapes by pouring water in a measuring cup or a similar vessel and measuring this initial amount of water. We then submerge our irregularly shaped object under water completely and measure by what amount the water has been displaced. This displaced volume is equal to the volume of the submerged object — an observation supposedly formulated by Archimedes. Using this method is only possible with objects that do not absorb water or that cannot be damaged by water.
We would not use it to measure a volume of a camera or an article of clothing, for example. According to legend, truthfulness of which is debated, Archimedes was given a task by the king Hiero II of Syracuse to check if the crown that the king commissioned a goldsmith to make, was made of gold. The king suspected that the goldsmith substituted the gold, that the king gave him, by a cheaper alloy, profiting from the difference. Archimedes could determine this by calculating the density of the crown and comparing it to the density of gold, known at the time.
Melting the crown was not a possibility, therefore he had to find a way to calculate the volume without altering its shape. The answer is 1. So 10 micrograms of vitamin D is equal to IU.
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