Question

What is physical quanties in physics? What are its two types scalars and vectors? How can we classify any physical quantities into scalars and vectors? Please explain clearly and little bit in an easy manner so that i can understand it properly especially scalars and vectors.

Answer 1

Dear student,
I have provided a detailed and simple description of physical quantities and its types with examples. Read two or three times. You'll learn more in higher classes.
A physical quantity is a quantity in physics that can be measured.
Examples of physical quantities are mass, amount of substance, length, time, temperature, electric current, light intensity, force, velocity, density etc.
Scalar quantity: The physical quantities which have only magnitude but no direction are called scalar quantity.


Description: The rod is 2 metres long’, the vessel contains 200 gms. Of water’ and we waited there for five hours’. In these expressions , 2 metre long , five hours , 200 gms , we have some ideas of magnitude of a length , mass , and a time . But length mass and time has nothing to do with any direction. Such quantities which gives the idea of some magnitude but are not associated with any direction are called scalar quantities.

Example : Volume, density, energy, , speed , mass, distance, work, time, power, electric current , mechanical advantage , pressure, etc are the examples of scalar quantities.



Vector quantity : The physical quantities which have magnitude as well as direction is called vector quantity.


Description: The car is moving is moving with a velocity of 40 km/hr ‘east’

here east is representing the direction of the car and 40 represents the magnitude of the car .So in this example both magnitude and direction are coming so definitely it is a vector quantity, because it fulfils the condition to be a vector . A very important thing with regard to vector is that it is represented by an arrow sign (→ ). If in a problem vector word is not mentioned but the arrow sign (→ ) is there it is a vector quantity.


Example : Displacement, velocity, acceleration, momentum, force, weight, temperature, electric field , magnetic field, retardation ,moment of force etc.