Scalar and Vector Quantities ? - Param Himalaya Physics
What is a scalar Quantity ? It's example :
A Physical quantity which is described completely by its magnitude or size is called a scalar quantity. Thus a scalar quantity has only magnitude and no direction.
Example of scalar quantities :
Length , Distance , Area , Volume , Mass , Time , Power , Energy , Speed , temperature etc.
Characteristics of scalar quantities :
- A scalar quantity can be represented by a number with proper units. The number represent the magnitude of the quantity. Example : 2 Kg. Here 2 is number and Kg is unit.
- The scalar quantities having similar units get added or subtracted by the usual rules of arithmetic. Example : 2m + 3m = 5m.
What is a vector quantity? It's example
A physical quantity which requires both magnitude ( or size ) and direction for its complete description is called a vector quantity. Thus , a vector quantity has both magnitude and direction.
Example of Vector Quantities:
Displacement , velocity , Acceleration , Force ,Weight , Momentum etc.
Characteristics of Vector Quantities:
1. Representation of a vector : A vector quantity can be represented by a number with proper units and a direction.
Example : 45 km/Hour toward south.
Here 45 - Number magnitude , KM/ Hour - Unit , South - Direction.
2. Notation : vector are written either in bold letters or as the letters having an arrow over them. A or A
3. The vector quantities having similar units but different directions are not added/ subtracted by ordinary arithmetical rules. If two or more vector quantities have the same units and the same direction, then their magnitudes get added/ subtracted by ordinary arithmetical rules.
How is a vector quantity shown graphically ?
A vector quantity can be represented graphically by an arrow where
* The length of the arrow represents the magnitude of the vector quantity.
* The arrowhead represents the direction of the vector quantity.
To show a vector quantity graphically , we should have the following information:
* The magnitude of the vector quantity
* The direction of the vector quantity.
Question: show a displacement vector of 2.5 m towards 30° west of North on a scale , 1 cm = 1 m.
Answer : we have 1 m = 1 cm
So , 2.5 m = 2.5 × 1 cm = 2.5 cm
This means the vector can be shown graphically by a line of 2.5 cm in the direction 30° west of North. Thus , the displacement vector is respresented by the arrow OA.