Physical Quantities 

- Before starting this topic in a conceptual manner the first question coming to our everyones mind that why we study this,what is use of this and why this all quantities and its units are in exist.
- So if you have queries like above then it is obvious. So lets start and clarify all the queries regarding this.

1) As we all know we are leaving in a world of science i.e. In this world every day a new technology , new concept are invent by any person at any place
2) And we know that this invention is use by any person at any place also
3) So if a person find something and he give some specification of that thing but in his own manner then
4) The people who want to know about that thing the respective person will personally give the specifications regarding this invention
5) So to avoid all this the seven basic  unit/quantity are going to exist and because of this now, if someone somewhere find something he will convert all his invention things specifications in this seven quantities
6) And because of this seven quantities are accepted in all over the world ,every one can imagin or understanding the features of that invention
7) Now if you think why this are only seven quantities not less or more than that , so the reason is this seven quantity can acquire all the terms and except this      nothing is found
            So I hope now you can study this


- All the quantities which can be measured directly or indirectly in terms of which law of physics are describe and whose measurement is necessary are called as physical quantities.

-Or we can say that,
 Physical quantity is a physical property of a phenomenon body or substance that can be quantified by measurement or we can say that quantities which we come across during our scientific studies are called as the physical quantities.

-The international system of units is an internationally agreed metric system of unit of measurement that has been in existence since 1960. The system itself is based on the concept of seven fundamental base units of quantity, from which all other units of quantity can be derived 

The seven base quantities and their corresponding units are :
- Length (meter)
- Mass (kilogram)
- Time (second)
- Electric current (ampere)
- Ehermodynamic temprature (kelvin)
- Amount of substance (mole)
- Luminous intensity (candela)

Fundamental and derived units:
- The unit of defined set of physical quantity called fundamental quantities are known as fundamental unit and
- The Unit for all other physical quantity except fundamental quantity are called as derived unit
e.g.-Unit of speed can be derived from the fundamental units as,
        Unit of speed =Unit of distance /Unit of time = m/s =ms^-1

Scaler and Vector quantities

- Physical quantity which have magnitude only and no direction are called as scaler quantity
e.g.- mass, speed , volume, work, power, energy, etc.

- Physical quantity which have magnitude and direction both are called as vector quantity
e.g. -displacement , velocy , acceleration , force, momentum, torque, etc.