When studying contents related to Physics, we often come across the word greatness defining scientific terms such as speed, acceleration, strength, time etc. One greatness it is everything that can be measured and allows us to have characteristics based on numerical and/or geometric information.
The so-called fundamental quantities are those defined exclusively through a physical standard established by the International System of Units (SI). We can understand by physical unit the pattern chosen to measure a quantity. The table below shows the fundamental quantities defined by the SI:
The so-called derived quantities are those defined from the fundamental quantities. These are the cases, for example, of velocity, which has its unit of measure derived from the units of length and time, as is the case of m/s (read meter per second), and force, which has as a unit the newton (N), derived from the units of length, time and mass (1N = 1 kg.m/s).
According to the form of characterization, the quantities are classified as scalar and vector:
scalar quantities: Are those defined only by a number followed by a unit of measure. These quantities need only the modulus information (numerical value) to be fully characterized. These are the cases, for example, of time, temperature and mass.
vector quantities: For the complete characterization of a vector quantity, three pieces of information are needed: modulus (numerical value), direction and direction. As an example of vector quantities, we can mention force, velocity, acceleration, etc. The vector is the oriented line segment that represents the vector quantities.
By Joab Silas
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/fisica/o-que-e-grandeza.htm