This belongs to the Chapter of Physical Quantities

1. TIPS FOR TAKING ONLINE CLASS
FOR YOURSELF
1: Be ready before the starting time
2: Treat an online course like a real course
3: Hold yourself accountable
4: Practice time management
5: Create a regular study space and stay organized
6: Eliminate distractions
7: Figure out how you learn best
8: Actively participate
9: Leverage your network
INSIDE THE CLASS
1: Open your camera
2: Mute your audio
3: take your pen, copy and other material sources
3: Don’t add your note on the screen
4: Do ask, write and share after the permission. It
will be provided at the end of the class
5: Be more disciplined.
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2. This is a REGULAR CLASS. Please make a
note by writing down what you have
seen here.
Make a separate note for CURRENT
ELECTRICITY.

3. UDAY KHANAL
Department of Physics
CCRC
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4. Physical Quantity
The quantity which can be measured by some physical means.
Example : Length, Weight
Note:
Love is not a physical quantity
Physical quantities obey physical laws. They are measurable.
Measurement of Physical quantity = Magnitude x unit [in which the quantity is measured]
Numerical value x unit
n x u
Length of a stick = 20 m
Here the unit of length is meter which is 20 times in its length

5. The product of each numerical value and its corresponding unit is constant:

6. Important features:

8. Fundamental unit:

9. Fundamental unit in different system of
measurement:
S.No. Quantity Unit Abbreviation
S.No. Quantity Unit Abbreviation

10. S.No. Quantity Unit Abbreviation
S.No. Quantity Unit Abbreviation

11. S.No. Quantity Unit Abbreviation

12. SI System (International System of Units)
This system is result of CGPM meeting in 1971.
Now-a-days this system is popular throughout the world

13. Definition of fundamental units:

14. Supplementary Unit:
The unit having no dimensions is supplementary unit.
e.g., Plane angle Radian
Solid angle Steradian
Kg.m/s2

15. S.No. Practical unit of Length Practical Unit of Mass Practical Unit of Time
Practical Unit:
A large number of units are used in general life for measurement of different
quantities in comfortable manner. But they are neither fundamental units nor
derived units.
Some practical units are listed below.

16. Factors Prefix Symbol
Some measurement are listed below:
Prefix for SI Units:

17. Measurements Length in meter

18. Measurements Time interval in
seconds

19. Object Mass in Kilogram

20. Dimensions and Dimensional Formula

22. Methods for finding Dimensional Formulae
Example: Find the dimensional formula for momentum

25. Some Workout

26. Some examples of derived physical quantities
S.No Physical Quantity Relation with other
physical quantities
Dimensional
formula
SI Unit

33. Uses of Dimensions

34. A) To check the correctness of a physical equations:

37. Example 1:

42. B) To derive new relation among physical quantities:
Homogeneity principle of dimensions is a powerful tool to establish the relation
among various physical quantities.

43. Combining; Tα lagb
T = K lagb

44. If centripetal force is a function of ‘m’ , ‘v’ and ‘r’ then find the relation:

45. C) To convert a physical quantity from one system to another:

46. 1000 g = 1 kg
[M] [M]

51. Significant figure

52. The essence of SCIENCE: ask an impertinent question, and
you are on the way to a pertinent answer.

53. DID YOU ENJOYE THE CLASS?
Leave your valuable suggestions so that I will be
better for you all in the next class. Your
suggestions are highly appreciated.
NO?
Yes?

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