We explain what the volume is, how this magnitude is measured and some examples. Also, what is density and mass.
What is the volume?
Volume is understood to be a metric, Euclidean and scalar type magnitude , which can be defined as the extension of an object in its three dimensions, that is, taking into account its length, width and height. The physical bodies all occupy a space, which varies according to their proportions, and the measure of that space is the volume.
To calculate the volume of an object, simply multiply its length by its width and height , or in the case of geometric solids, apply certain formulas based on the area and height or other similar variables. For example:
- Volume of a parallelepiped. v = lxbxh, where l is length, b is width and h is height.
- Volume of a cube. v = a3 that is, where a is the area of the cube, olxlx l.
- Volume of a sphere. v = 4/3 x π x r3, where r is the radius.
- Volume of a cylinder. v = π x r2 xh, where h is the height of the cylinder.
- Volume of a cone. v = (π x r2 xh) / 3, where r is the radius of the base.
- Volume of a pyramid. v = 1/3 xaxh, where a is the area of the base.
On the other hand, depending on the state of aggregation of matter and also its temperature, the volume may manifest itself in one way or another . Thus, a physical body has a fixed and determined volume, unchanging, while fluids ( liquids and gases ) do not, adapting to the space that contains them. In addition, the temperature directly influences the volume of gases and liquids, causing them by their nature to expand in the presence of heat and contract in the presence of cold.
How is volume measured?
The unit established in the International System (SI) to measure volume is the cubic meter (m3) , although liters are used to measure capacity (equivalent to volume but in the presence of fluids). This distinction is due to historical reasons, but they are equivalent, since one liter (L) equals one cubic decimeter (dm3). This means, in addition, that one can also speak of cubic kilometers or cubic millimeters, depending on the need.
In the Anglo-Saxon system of measurements, the volume will be measured using feet, inches or cubic yards , or for liquids the barrel, the gallon and the pint. In a culinary environment, it is possible to find as a measure of the volume a cup, a tablespoon or a teaspoon, which are less precise, but much more practical.
On the other hand, to measure the volume of a fluid in a laboratory , precipitated vessels or test tubes are used , while to measure the volume of a solid it must be immersed in a test tube with water , whose volume we know, and introduce into the solid, to be able to measure the increase in the whole volume. Then the initial volume will be subtracted and the volume of the solid added will be taken.
To exemplify what the volume is, the capacity of various containers can be used . For example, a glass, a cup and a bottle have different capacities that represent the volume of space in its forms. Another example is the measurements of different materials that are used in a chemical laboratory to carry out an experiment, such as the cubic centimeters of a solid or the liters of a gas or other fluids.
Density is a scalar magnitude that reflects the amount of matter of a solid object (that is, its mass) distributed in its volume (that is, the space it occupies). It is usually represented with the Greek letter rho (ρ) and it is calculated, on average, as the difference between mass and volume of the object: ρ = m / V. The unit of density measurement according to the International System is the kilogram per cubic meter (kg / m3).
When we talk about mass, we mean a magnitude that expresses the amount of matter present in a body , measured by the inertia it presents (that is, its resistance to acquiring an acceleration against the action of a force). It is an intrinsic property of matter, which is measured according to the International System (SI) in kilograms (kg) and is expressed by the variable m.
This measure should not be confused with the amount of substance , which is chemically calculated in moles ( mol ); nor with the weight , which is a vector magnitude that represents the intensity with which the force of gravity acts on a body, measured according to the International System in Newtons (N).