# Vectors and Scalars

Vectors and Scalars:

Vectors and scalars are the two classification of physical quantities in physics.

Physical quantities are divided into vectors and scalars according to the range of information denoted by the quantity.

Vectors:

If we need to denote the motion of an object along a straight line we can take it’s motion to be positive in one direction and negative in another , But if we need to denote the motion of an object in two or three dimensions then it is not possible to denote direction of the motion using simple positive or negative numbers. So we need to introduce vectors here.

A vector is a quantity which have both magnitude and direction.

Vectors follow certain rules of combination and we cannot use simple algebra to do vector addition , subtraction  , multiplication and division.

The simplest example of Vector is Displacement vector.

A displacement vector is the vector which depicts the motion of an object , it depicts the total Displacement of the object and the direction of the motion.

A displacement vector from Point “A” to “B” is denoted by:

$\overrightarrow{AB}$ and is read as “vector  a b”

We can also represent as vector using an italic letter like: “a” , “b” , “c”

We can Represent the Displacement vector in image or geometrically as:

vectors and scalars : Displacement Vector

Scalars:

Not all physical quantity evolves both magnitude and direction , We can denote some physical quantities only by it’s magnitude such a quantity is called scalar quantity.

For example Pressure , Temperature , Distance etc.

While representing a length or distance we can represent it by simple numbers like “5 meters” , “- 20 meters” , “- 4.5 Km” etc. , It don’t have any direction associated with it so it is called scalar.

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