From the Latin quantitas, quantity is the portion of a magnitude or a certain number of units. For example: “We need more money to move”, “Please don’t serve me so much food that I have to go back to the office later”, “I think in this World Cup, we are going to spend a good amount of scares in each game “, ” That amount is more than enough to conform to anyone.
Quantities are expressed in different ways depending on the magnitude in question. A quantity of weight can be expressed in grams (“I am not going to carry a lot of textured soybeans: with two hundred grams it is enough”), while a quantity of length can be reflected in kilometers (“You still have a good amount of kilometers to go before reaching the reservoir ”).
Quantities can be homogeneous (when they are made up of objects of the same species), heterogeneous (made up of different species or substances), continuous (their parts cannot be separated) or discrete (their components are dispersed).
In some cases, the amount in question must be handled accurately to avoid inconvenience. If a person wants to buy a car, he will need a certain amount of money. If this amount is not collected, you will not be able to complete the operation.
In other situations, however, the amounts may be estimates or subjective (such as the amount of salt in a recipe or the number of changes that should be taken on a trip). These are situations in which the taste of each person comes into play, as well as a series of cultural issues, and any possibility is valid as long as it is accepted by whoever considers it.
Among the popular sayings that use this term is “quantity does not make quality “, with its variations, typical of each Spanish-speaking region. It is often used on a sentimental level (alluding, for example, to the number of friends) as well as materially (“a quad-core processor does not necessarily offer better results than a two-core”).
Amount of movement
It is known as quantity of movement, momentum, momentum or linear momentum to a fundamental physical magnitude used in mechanical theories to describe the movement of bodies. For classical mechanics, its definition is achieved by multiplying the mass of a body by its speed at a given point in time.
Its origins date back to the seventeenth century, more precisely from the work ” Discourses and mathematical demonstrations around two new sciences “, published in 1638 by Galileo Galilei, in whose pages he refers to the concept through the term “momentum”.
Depending on the mechanical formulation taken into account, the specific definition of momentum is different:
* Newton’s mechanics define it for a particle by multiplying its mass by its speed;
* Hamiltonian or Lagrangian mechanics plasma, in non-Cartesian coordinate systems, forms of greater complexity;
* the theory of relativity contemplates a definition of greater complexity even if inertial systems are used;
* Quantum mechanics requires for its definition the use of self-adjoint operators that are defined on an infinite vector space.
In general, Newtonian mechanics obtains the momentum and then looks for the relationship between it and Newton’s laws (“Law of force,” “Law of inertia,” and so on). However, modern physics brought with it a series of new points of view, and the advantages of such procedures when working with momentum were questioned.
Mainly, it was shown that this fundamental magnitude is a property belonging to every physical entity, whether it has mass or not (as can be seen in the case of photons and fields). The Newtonian formula is based on the product of mass and velocity, thus ignoring any non-mass body.