Mass vs Density
Mass and density are physical properties of any substance, and hold great significance for not only the substance, but also its use and application by human beings. Though it is easy to see physical properties like length, breadth, and height more readily than mass and density, these properties are actually more important for substances. Mass reflects the amount of stuff or material an object is made up of, whereas density reflects the space that this stuff requires or fills. Though the difference between mass and density looks quite simple and innocuous, there are subtle differences that will also be covered in this article.
We all know that a piece of rock, has a higher density than a ball of paper of the same size. This is because of the relative heaviness of objects with a constant volume. Though both the paper ball and the rock piece have the same volume, rock is heavier than paper. Density also refers to, how closely packed the molecules of the substance are. This obviously means that a cup made of foam is less dense than a cup made of ceramic. In the simplest of definitions, density of a material is its mass per unit volume.
You must be aware of the practice of comparing densities of substances with the density of water. This is because the density of water has been taken as one, and thus, an object having a higher density will sink in water, while an object having a density less than water will float on it. Thank God, oil has a density lower than water, or otherwise oil spills from tankers would have sunk inside oceans, killing all water creatures. Spilled oil keeps on floating on water, which can be collected through different means.
The concept of difference between mass and density is of great help in describing how a ship having a huge mass floats on water. No matter how large or heavy a ship may be, it will not sink as long as its density is leas than 1.0 g/cc. Though a ship may have a lot of steel in its construction, making it heavy, it has a larger volume thus keeping its density down to below 1g/cc forcing it to float on water.
Why do you think magma finds its way up to the mouth of the volcanoes? Just because, this molten rock mixture is lighter than surrounding rocks, magma comes up and spreads out of the volcano in the form of lava. One very interesting application of mass and density is seen in ocean water, where water at the surface is warmer than water at the bottom. This is because, warm water is lighter than cold water and thus, rises up to the surface.
Perhaps the best example of difference between mass and density is exemplified by hot air balloon. When air is heated, it becomes less dense, and the balloon begins to float on the cooler, denser air as soon as its density becomes less than that of the atmosphere.
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In brief: Difference between Mass and Density • There is no need to remain confused by the terms mass and density, and heavier or lighter merely reflects the mass or weight of the object • The concept of density tells us how much of materials is packed in unit space thus, making a substance denser. • Substances denser than water sink in water, whereas substances having less density than water float upon water. • The density of a large ship, even though a lot of steel goes into making it remains leas than 1g/cc making it float on water.
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