The Scalar Quantity
The scalar quantity is any positive / negative physical quantity that can be completely specified by its magnitude.
ex. Time , Length , Mass
The Vector Quantity
The vector quantity is any physical quantity that can not be completely specified unless we know both its magnitude & direction.
ex. Force , Moment
How to represent a Vector
Graphically:-
- Length of arrow = Vector's magnitude.
- Tip / head of arrow = The sense of vector's direction.
- The angle θ between the vector & a fixed axis = The direction of the vector.
In print:-
- A (boldfaced) = the vector.
- A (Italicized) = the vector's magnitude.
Handwriting:-
- ̅A (arrow or line above) = the vector.
- A (no arrow or line above) = the vector's magnitude.