The concept of length has its origin in the Latin word longitudo and is intended to name the magnitude physical that allows marking the distance that separates two points in space, which can be measured, according to the International System, using the unit meter.

To cite concrete examples of use: “I need a wooden shelf with a length of 40 centimeters”, “This table has a length of more than 50 centimeters, I don’t think it will fit into our kitchen”, “The length of the bed barely leaves room to pass”.

It is also interesting to mention that the wavelength It is the separation between two points that belong to the same phase of two consecutive waves. This length is inversely proportional to the frequency of the wave: so it can be established that the long wavelength is associated with a low frequency, while the short wavelengths correspond to a low frequency. frequency high.

On the other hand, it must be said that the vertical length is popularly referred to as height and the horizontal length in turn, it is associated with broad: “This closet has a height of 1.8 meters” is a more common phrase than “This closet has a vertical length of 1.8 meters”. In the same way, it is often said “The width of this table does not exceed 70 centimeters”, instead of “The horizontal length of this table does not exceed 70 centimeters”.

Latitude and longitude

When an airplane pilot or the captain of a cruise ship wants to communicate their position on the planet through the radio, they have two numerical values, which make up a coordinate, called latitude and longitude. These are angles, which are measured in degrees, minutes and arc seconds. Said nomenclatures, however, can be shortened according to the context, omitting “of arc”, as long as it is understood that time is not being talked about.

The lines of latitude cut the earth from one side to the other, and measure the angle that is formed between any part of the planet and its center. In this way, the globe has a series of rings that surround it, where the one that passes through the equator has the largest diameter and those located at the poles are just points.

To to size the latitude of a point on the earth, it is necessary to calculate the angle formed by the radius that goes to that point and that of the equator; if the site in question is above or below the latter, it speaks of north or south latitude, respectively.

On the other hand, there is a series of lines that join the poles and that have constant length; they are called meridians. They all cross the equator, which is divided into 360 degrees; In this way, to know the longitude of a given point, it is enough to know at what angle of the latitude in question the meridian falls.

The call zero length it passes through the Royal Astronomical Observatory of Greenwich, located in London, England. This center has been turned into a museum, where people are used to photographing themselves, attracted by the metal line located in its courtyard, which represents the Greenwich meridian.

Both the equator line and zero longitude divide the planet into four hemispheres: North South East and west. In addition, the name meridian has its origin in Latin and its meaning is close to that of “noon”, which led to the expressions “before meridian” and “post meridian”, whose initials are used when telling time, when it is not. It is in 24 hour format. In turn, in each line of longitude, a time difference is appreciated, which is measured by taking Greenwich as point reference, whether to add or subtract sixty minutes.