Question

principles of SI base units and SI derived units

Note:

Examples and explanations must have more than 300 words

Answer 1

The International System of Units (SI) consists of seven basic units, or fundamental units, that define the corresponding fundamental physical quantities, which have been chosen by convention, and which allow expressing any physical quantity in terms or as a combination of them. The fundamental physical quantities are complemented by two more physical quantities, called supplementary. Combining the basic units, the other units are obtained, called units derived from the International System, and which allow defining any physical quantity.

Fundamental Physical Magnitudes

Length

International System Basic Unit (S.I.): meter (m)

Definition: one meter is the length that light travels in a vacuum during a time of 1/299792458 of a second.

Mass

International System Basic Unit (S.I.): kilogram (kg)

Definition: A kilogram is a mass equal to that of a cylinder 39 mm in diameter and height, made of an alloy of 90% platinum and 10% iridium, located at the International Bureau of Weights and Measures, in Sèvres, France.

Time
International System Basic Unit (S.I.): second (s)

Definition: one second is the duration of 9 192 631 770 oscillations of the radiation emitted in the transition between the two hyperfine levels of the ground state of the 133 isotope of the cesium atom (133Cs), at a temperature of 0 K.

Electric current intensity
International System Basic Unit (S.I.): amp (A)

Definition: an ampere is the intensity of a constant current between two parallel, rectilinear conductors, of infinite length, of negligible circular section and located between them at a distance of 1 meter in vacuum, which would produce a force equal to 2 x 10- 7 newtons per meter of conductor length (N / m).

Temperature
International System Basic Unit (S.I.): kelvin (K)

Definition: Kelvin is the fraction 1 / 273.16 of the thermodynamic (or absolute) temperature of the triple point of water (273.16 K).

Amount of matter
International System Basic Unit (S.I.): mol (mol)

Definition: a mole is the quantity of elemental units (atoms, molecules, ions, etc.) in a material system that is equal to the number of atoms existing in 12 grams of the carbon-12 isotope. This number of elemental units is a constant that does not depend on the type of material of value 6.02214179 · 1023, and is known as Avogadro's Number.

Luminous intensity
International System Basic Unit (S.I.): candela (cd)

Definition: The candle is the International System unit of measure for light intensity, which is understood as the luminous flux emitted per unit of solid angle in a specific direction. The candle, as a measure of light intensity in a given direction, corresponding to an energy of 1/683 W / sr (watts per steradian) from a source that emits monochromatic radiation with a frequency equal to 540 · 1012 Hz.

Supplementary Physical Magnitudes

Flat angle
International System Basic Unit (S.I.): radián (rad)

Definition: a radian is the angle that limits an arc of circumference whose length is equal to the radius of the circumference.

Solid Angle
Basic Unit International System (S.I.): estereorradián (sr)

Definition: the stereoradian is the solid angle that, having its vertex in the center of a sphere, delimits on the spherical surface corresponding to an area equal to that of a square whose side is the radius of the sphere.

Derived Units

Force

International System Basic Unit (S.I.): Newton (N)

Definition: a newton is the force necessary to provide an acceleration of 1 m / s2 to an object whose mass is 1 kg.

N = kgm / s2.

Energy
International System Basic Unit (S.I.): Joule (J)

Definition: A Joule represents the energy required to move an object a distance of one meter by applying a force of one Newton; that is, it is a magnitude of force per distance.

J = N · m = (kg · m / s2) · m = (kg · m2) / s2.

Power
International System Basic Unit (S.I.): watt (W)

Definition: A watt is the power that generates an energy of one Joule per second. In electrical terms, a watt is the power produced by a potential difference of one volt and an electric current of one ampere.

W = J / s = V · A = (m2 · kg) / s3.

Pressure
International System Basic Unit (S.I.): Pascal (Pa)

Definition: A pascal is the normal (perpendicular) pressure that a force of one newton exerts on a surface of one square meter.

Pa = N / m2 = kg / (s2 · m).

Dynamic or absolute viscosity
International System Basic Unit (S.I.): kg / (ms), or N · s / m² (Pa · s)

Definition: Dynamic or absolute viscosity measures the internal resistance of a fluid to flow, or in other words, quantifies the degree of opposition of a fluid to tangential deformations. The dynamic viscosity of 1 Pa · s for a homogeneous fluid, in which, when there is a speed difference of one meter per second between two parallel planes separated by one meter, the rectilinear and uniform movement of a flat surface of one square meter causes a retarding force of one newton.

Kinematic viscosity
International System Basic Unit (S.I.): m2 / s

Definition: Kinematic viscosity is defined as the ratio of the absolute viscosity to the density of the fluid.

Surface
International System Basic Unit (S.I.): square meter (m2)

Definition: A square meter is the area equivalent to that of a square of one meter per side.

Volume
International System Basic Unit (S.I.): cubic meter (m3)

Definition: a cubic meter is the volume of a cube of a meter of edge.

Velocity
International System Basic Unit (S.I.): meter / second (m / s)

Definition: one meter per second is the speed of a body that, with uniform movement, travels a length of one meter in one second.

Acceleration

International System Basic Unit (S.I.): meter / second2 (m / s2)

Definition: it is the increase that a body experiences its speed in the amount of one meter per second every second.

Density
International System Basic Unit (S.I.): kilogram / meter3 (kg / m3)

Definition: is the amount of mass (kg) contained in each cubic meter of volume. Or put another way, it is the relationship between the mass of a body and the volume it occupies.

Electric charge
International System Basic Unit (S.I.): coulomb or coulomb (C)

Definition: represents the amount of electric charge transported in one second by a current of one ampere of electric current intensity (1C = 1A · s).

Electric resistance
International System Basic Unit (S.I.): Ohm (Ω)

Definition: An ohm is the electrical resistance that exists between two points of a conductor, when applying a constant potential difference of 1 volt causes a current of intensity of 1 ampere.

These are the main derived units