What is Unit and Measurement in Physics - Easy language

What is Unit and Measurement in Physics - Easy language

Aditya Raj Anand

Saturday 28 May 2022

Physics

In this post we will discuss about the very first topic of physics unit and measurement. means the starting phase of physics. If you to the even big universities, your physics professor start your first class with this topic i.e, unit and measurement. So, you can imagine how important this chapter is.

So, if you are a physics student then you must have to know these two topics. first is unit and second is Measurement because this is the base of the physics.

Unit and Measurement Introduction:- 

Physics:-  The study of nature and natural things.

• It is the made of greek word " Fusis" means natural things and nature.
• It means that physics is the study of nature and its laws.
• Physics is the foundation of engineering and technology.
• Physics is based in experiment when experiments are done then it measure with the help of physical quantity.
• Quantity means it represents the number.

Physical quantity:- It is represent of the physical laws in the term id quantity.

• It is of two types
• Scalar quantity and vector quantity.
• Scalar quantity means it has only magnitude not direction.
• vector quantity means it has both magnitude and as well as direction.

What is Unit?

A unit is defined as the single word or a symbol that supports a physical and derived quantity. On other words, A unit is defined as a single things of a group of things. like a building of 10 rooms is expressed in unit as single room. 

In other words, a 2 meter wide and 5 meter high wall has a unit of one bricks. In Physics Unit has its own identity. means without unit we cannot define the magnitude of acceleration, velocity, motion, etc.

It is of two types

• Fundamental unit
• Derived unit

1.     Fundamental unit:- It is not depend another unit, three fundamental unit are mass, length and Time.

2.     Derived unit:- It is depend in fundamental unit.

system of unit are four types

1.     Mks system:- In this system Length, Mass and Time are expressed in meter, Kilogram, and Second.

2.     Fps system:- In this system Length, Mass and Time is expressed in Foot, Pound, second.

3.     CGs system:- In this system Length, Mass and Time is expressed in Centimeter, Gram, second.

4.     S.I system;- ( international System of Unit )  In S.I system having seven fundamental unit.

 

Some examples of physical quantities with their si units and cgs units

Here is a collection of 5 fundamental and derived physical quantities which commonly used in physics with their si units and CGS units. Also describe the derived quantity with derivation.

We have already discussed about the definition of physical quantity in the above definition. But lets define the physical quantity in another words.

Physical quantity are those quantities which represents the quantities of any material with the help of some symbols attached with numerical values. For example a container contains 6 kilograms of wheat. So we can write 6 kg. Here kg is the physical quantity attached with numerical value of 6.

As we have already seen above that, Physical quantities are two types first is fundamental quantity and second is derived quantity. These are the following 5 physical quantities (both fundamental and derived) with their si units and CGS units. Before we start discussing following 5 physical quantities. Please note that some quantities are derived from fundamental quantity.

1. Mass
2. length
3. Time
4. Acceleration
5. Velocity

What is measurement?

Measurement is defined as, it is a fixed number or quantity of any substance, objects, or things that depends on a definite universal or a particular objects.

For example, lets suppose we have to measure our body temperature. So, we use thermometer because thermometer is a universal or a particular object that the whole world use for measuring temperature in