QUANTITIES AND UNITS

11 Sep 2009

A. Basic Quantities and Derived Quantities

In physics there are two kinds of physical quantities, those are basic quantities and derived quantities. Basic quantities are the physical quantities the units of which predetermined, while the derived quantities are the physical quantities which the units of which are derived from basic quantity units.

1. Basic Quantities

To communicate the result of a measurement of a certain physical quantity, a unit for the quantity must be defined. In 1960, an international committee agreed on a standard system of units for the fundamental quantities of science, called SI (Systme International). The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent

Base quantity Name Symbol
length meter m
mass kilogram kg
time second s
electric current ampere A
thermodynamic temperature kelvin K
amount of substance mole mol
luminous intensity candela cd

SI Base Units

The SI unit system consists of seven base units, with a number of other units derived from those foundations. Below are the base SI units, along with their precise definitions, showing why it took so long to define some of them.

Length

The base unit of length;In 1799, the legal standard of length in France became the meter, defined as one tenmillionth of the distance from the equator to the North Pole.

Mass

The SI unit of mass, the kilogram, is defined as the mass of a specific platinumiridium alloy cylinder kept at the International Bureau of Weights and Measures at Svres, France

Time

Before 1960, the time standard was defined in terms of the average length of a solar day in the year 1900. (A solar day is the time between successive appearances of the Sun at the highest point it rea-ches in the sky each day.) The basic unit of time, the second, was defined to be (1/60)(1/60)(1/24) _ 1/86 400 of the average solar day

2. Derived Quantities

Other quantities, called derived quantities, are defined in terms of the seven base quantities via a system of quantity equations. The SI derived units for these derived quantities are obtained from these equations and the seven SI base units. Examples of such SI derived units are given in Table 2, where it should be noted that the symbol 1 for quantities of dimension 1 such as mass fraction is generally omitted.

Table 2. Examples of SI derived units

SI derived unit

Derived quantity Name Symbol
area square meter m2
volume cubic meter m3
speed, velocity meter per second m/s
acceleration meter per second squared m/s2
wave number reciprocal meter m-1
mass density kilogram per cubic meter kg/m3
specific volume cubic meter per kilogram m3/kg
current density ampere per square meter A/m2
magnetic field strength ampere per meter A/m
amount-of-substance concentration mole per cubic meter mol/m3
luminance candela per square meter cd/m2
mass fraction kilogram per kilogram, which may be represented by the number 1 kg/kg = 1

A. Dimensional Analysis

The term dimension is used in physics to describe the methods or arrangement of derived quantities from basic quantities. The dimensions of basic quantities is written in a capital letter and put in brackets. Look at the bracket


TAGS


Comment
  • hermes belts shops 4 years ago

    I do love the way you have presented this particular situation and it does indeed offer me a lot of fodder for thought. Nonetheless, from what precisely I have seen, I just simply hope when the commentary pile on that men and women remain on issue and in no way get started on a soap box associated with some other news du jour. All the same, thank you for this outstanding point and though I do not really agree with the idea in totality, I respect the point of view.

  • ferragamo bags 4 years ago

    This web site is really a walk-through for all of the info you wanted about this and didn’t know who to ask.Glimpse here, and you’ll definitely discover it.

  • [BLOCKED BY STBV] machu picchu 5 years ago

    Title…

    Wow, I\’m really chuffed that I clicked on this page, great info here! Better than http://facebook.com!…

  • penis enlargement pills 6 years ago

    brinkka2011 says: Congratulations on having 1 of the most sophisticated blogs Ive arrive throughout in some time! Its just incredible how much you can take away from a little something simply because of how visually beautiful its. Youve put collectively a great blog space great graphics, videos, layout. This is unquestionably a must-see blog!

  • WeigueGlolley 6 years ago

    You are not right. I am assured. Let’s discuss. Write to me in PM, we will communicate.
    19,178 Identity Theft Victims Per Day - Are You On

  • WoodsJoy 6 years ago

    I received 1 st mortgage loans when I was very young and it supported my business a lot. However, I require the financial loan also.

  • slaskixecress 6 years ago

    thanks for the interesting information

  • tabletkiodchudzanie 6 years ago

    Wielu z was pewnie trapi problem nadwagi. Tym ktorym powiodlo sie zrzucenie paru kilogramow napewno zdazylo sie poznac znany efekt yoyo. Cala wasza praca poszla na marne. Probujecie wielu srodkow i waga nie spada. Az w koncu wpadacie na pomysl, aby wziac jakies skuteczne tabletki na odchudzanie. Tylko ktore kupic ? Z wielu moich doswiadczen, moge polecic wam Thermacuts. Zuzywa tluszcz zamieniajac go w energie i redukuje jednoczesnie apetyt. Nie trzeba trenowac aby uzyskac szybkie efekty. Kiedy dodatkowo bedziemy uprawiac jakis sport efekty dzialania Therma Cuts zwiekszaja sie. Skladniki Therma Cuts sa obojetne dla zdrowia, bo sa naturalne!

  • sportingbetpromo 6 years ago

    ayobelajarfisika.blogdetik.com is cool !!
    sportingbet.com

  • downloadfromyoutube 6 years ago

    ayobelajarfisika.blogdetik.com is my favorite website now!
    how to download from youtube

  • Dr Metaphysics 7 years ago

    Just found this post on Google - do you have any other similar posts?

  • wheyp.roteinsideeffects 7 years ago

    Very outstanding website.
    The info here is very important.

    I will refer it to my friends.

    Cheers

  • Forex Autopilot 7 years ago

    I somehow dont agree with a few things, but its great anyways.

  • whey.protein.side.effects 7 years ago

    Very outstanding place.
    The content here is really useful.

    I will tell my friends.

    Cheers

  • baraErose 7 years ago

    I am always looking for brandnew informations in the internet about this theme. Thanks!!

  • tedy 7 years ago

    Only 34 days before DOFUS 2.0! December 2nd will be here before we know dofus kamas. On dofus kamas moins chers every player will discover a completely new DOFUS experience. acheter des dofus kamas have to be content with the reports and forums. Even so achat dofus kamas, theres always a few of our dear players in the forums.

  • forexstrat_egy 7 years ago

    I am definitely bookmarking this page and sharing it with my friends.

    :)

  • Insipaffisiow 7 years ago

    Why hello swain forum people! I straight wanted to set up myself here as this looks like a dialect right interesting forum! I myself am provocative in things like writeing and computer fixing up so if anyoune needs steal reveal me know! I also Suffer from Sciatica so if you aslo have this condition suffer to me have knowledge of so we can allowance some stretches!

  • Unfaifsacisse 7 years ago

    Hey everyone just wanna say hello and introduce myself!

  • Insipaffisiow 7 years ago

    Hey there everyone i was just introduceing myself here im a first time visitor who hopes to become a daily reader!

  • moguefratemor 7 years ago

    Hey there everybody i know you’ve all probably heard this already but check out google for all the scandal thats been going around about her lately
    basically she first claimed that the tape was for a boyfrind in highschool at which time she begged him to tell the media she was 17 at the time. This morning on tmz they talked about a voice interview where the man who had the video insists that she was 20 at the time.

    You can check out the newest tmz story and pictures here. http://photos.tmz.com/galleries/carrie_prejean_san_diego_romp#55556

    So i know theres a lot of bullshit going around on the internet but i finally found the actual video. SO CHECK IT OUT SHES HOT AS HELL but all in all just another homeade sex video. The link is http://tinyurl.com/ye95zu7

  • The Buzz » Blog Archive » VanIshed Jones; Just the Tip of the Obama Iceberg? | Full Circle … 8 years ago

    [...] Fisika SMAN 1 Bangil Blog Archive QUANTITIES AND UNITS [...]

-

Author

Follow Me


Archive