The unit and measurement | physics

Here in this blog content , we will go to learn more about this unit and measurement .

So before we learn about unit and measurement , let's talk about field of measurement .

1) Physics 

2) physical quantity

3) units

4) Measurement 

So here , let's know about this given concept one by one .

1) Physics : The physics defined as , it is the branch of science , which deals with study of matter and natural phenomena .

2) Physical quantity : The physical quantities defined as , the quantity which are included in the physics is called as or known as physical quantities .

For an example : i) Length , ii) Mass , iii) Time , iv) Temperature , v) Velocity , etc.

3) Unit : The unit is defined as , the standard which are used for measurement purpose of physical quantities is called as or known as unit .

 4) Measurement : The measurement is defined as , the comparison of unknown quantity with respect respect to fixed quantity is called as or known as measurement . 

So let's known about , what is the requirement of unit ?

i) The first requirement of unit is , it should be universally accepted .

ii) The second requirement of unit is , it should be invariable with time and place .

iii) The third requirement of unit is , it should be well define .

iv) The fifth requirement of unit is , it should not be too large or too small .

v) The sixth requirement of unit is , it should be reproducible .

vi) The seventh requirement of unit is , it should be easily convert into smaller unit .

* Let's know about ,

a) Fundamental quantities : So the fundamental quantities is defined as , the quantity , which does not depends on any other quantities for their measurement is called as or known as fundamental quantities .

b) Fundamental unit : The fundamental unit is defined as , the unit of fundamental quantity is called as or known as fundamental unit .

What are the seven fundamental quantities ?

Fundamental quantities     Fundamental unit

1) Length                                    m ( metre ) 

2) Mass                                        kg ( kilogram )

3) Time                                        s ( second ) 

4) Temperature                         k ( kelvin ) 

5) Electric current                     A ( ampere )

6) Luminous intensity              cd ( candela )

7) Amount of substance           mole

                        

c) Derived quantity : The derived quantity is defined as , the quantity which depends upon one or more fundamental quantities is called as or known as derived quantity .

d) Derived unit : The derived unit is defined as , the unit of derived quantity is called as or known as derived unit .

So let's see the example of this derived quantities .

Derived quantity                 Derived unit

1) Area                                        m^2

2) Volume                                   m^3

3) Velocity                                   m/s

4) Acceleration                           m/s^2

5) Speed                                       m/s

6) Pressure                               N/m^2 or pascal

7) Impulse                         N.s (newton second)

8) Momentum                         kg . m/s

9) Stress                                    N/m^2

10) Strain                               strain has no unit

11) Frequency                         hertz ( Hz )

12) work                           kg . m^2/s^2  or joule

13) Power                          watt or joule/second

   etc...          

* What is systems of unit ? 

Ans : A set of fundamental unit and derived unit is called as or known as system of unit .

There are units are available in different groups . The system of units , which are used in C.G.S , M.K.S , F.P.S , and S.I . Here length mass and time are taken as basic physical quantities , using these basic quantities many physical quantities are derived .

1) C.G.S : Here in this C.G.S system , the unit length , mass and time are take as centimetre , gram and second respectively .

2) M.K.S : Here in this M.K.S system , the unit length , mass and time are taken as metre kilogram and second respectively .

3) F.P.S ( British system ) : Here in this F.P.S system , the unit length , mass and time are taken as foot pound and second .

4) S.I : Here in this , the S.I it is the abbreviation of international system of unit.

* So here , let's know about rules to write the unit ,

1) The unit name after scientist are not written with a capital letter .

For an example :

Right this one --  i) newton , ii) henry , iii) watt , etc.

Not right this one -- i) Newton , ii) Henry , iii) Watt , etc.

2) The symbol of unit name after scientist should be written in capital .

For an example : i) N - for newton , ii) H - for henry , iii) W - watt , etc.

3) Small letters are used as symbol for unit .

For an example : i) kilogram - kg , ii) metre - m

4) There is no full-stop or any punctuation mark should be used before or after the symbol of unit .

For an example :

Not right -- i) 40 m;   ii) 40.m   iii) 40m.

Right this one -- i) 40 m ii) 40 m  iii) 40 m

And last one is ,

5) The symbol of unit is always written in singular form .

For an example :

Right this one -- i) 1kg   ii) 10kg

Not right --     1kgs  ii) 10kgs

* So let's see the significant figures ,

The digit from ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ) which are useful for assigning a true value to result is called as or known as significant figure .

So we learn ' Rules to write this significant figures '

1) So here in this all the digit from ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ) are significant figures .

2) The second ones is , the zero become significant , if it comes in between two non-zero digits .

For an example : i) 102 km   ii 101 litre water

3) In the third rule , the all zero to the right side of decimal point and left side zero digit are non-significant .

For an example : i) 0.0123 -- 3 significant  figure

4) In the fourth rule , the zero is significant , if it is to the right side of non-zero digit after decimal point .

For an example : 0.2300 --. 4 significant figure

5) And in the fifth rule , if zero is in right side of the non-zero number than it may be significant or may be not .

For an example : i) 0.00476  -- 3 significant figure

ii) 1.024  -- 4 significant

* So let's learn about , what is an error ,

Error : So an error is define as , a fault or mistake can be observed even after most careful observation are taken for measurement is called as or known as error.

So here we will go to learn about the different types of error ,

1) Instrumentation error : In instrumentation an error causes due to faulty instrument is called as or known as instrumental error . 

So how we can fix this type of an instrumentation error ?

Ans : we actually fix this type of instrumentation error , by replacing faulty instrument with another instrument .

2) Systematic error : Systematic type an error cause due to faulty setting by the observer or an experiment is called as or known as systematic error .

So how we can fix this type of an error ?

Ans : So we can fix this systematic error or minimize this systematic error by identifying it's causes .

3) Random error : Random type an error causes due to climatic condition and human limitation is called as or known as random error .

So how we can fix this type of Random error?

Ans : We fix this Random error or minimize this Random error , by performing multiple time of an experiment and taking large number of reading . So that we can fix or minimize this type of an error .