4.1 Vector


(A) Definition of Vector and Vector Notation
1. Vector is a quantity that has both magnitude and direction.
2. Scalar is a quantity that has magnitude only.
3. A vector can be presented by a line segment with an arrow, known as a directed line segment.





(B) Equality of Two Vectors
1. Negative vector of   A B has the same magnitude as   A B but its direction is opposite to that of A B .


2. A zero vector is a vector whose magnitude is zero. It is denoted by 0 ˜ .

3. Two vectors are equal if both the vectors have the same magnitude and direction.