Physics > Basic Vectors > 8.0 Cartesian co-ordinate system

  Basic Vectors
    1.0 Introduction
    2.0 Representation of vector
    3.0 Basic definition related with vectors
    4.0 Types of vectors
    5.0 Angle between the vectors
    6.0 Addition of vectors
    7.0 Subtraction of vectors
    8.0 Cartesian co-ordinate system
    9.0 Resolving vector into its components
    10.0 Dot product of two vectors
    11.0 Cross product of two vectors

8.3 Displacement vector

Consider two points $A$ and $B$ with coordinate $\left( {a_1,b_1,c_1} \right)$ and $\left( {a_2,b_2,c_2} \right)$ respectively.


Now the particle moves from point $A$ to $B$.

So, $\overrightarrow {AB} $ will be the displacement vector as shown in the figure.


In $\Delta OAB$, from triangle law of vector addition we can write,
$$\overrightarrow {OA} + \overrightarrow {AB} = \overrightarrow {OB} $$$$\overrightarrow {AB} = \overrightarrow {OB} - \overrightarrow {OA} $$
We can write,
$$\overrightarrow {OA} = {a_1}\widehat i + {b_1}\widehat j + {c_1}\widehat k$$$$\overrightarrow {OB} = {a_2}\widehat i + {b_2}\widehat j + {c_2}\widehat k$$ As, $$\overrightarrow {AB} = \overrightarrow {OB} - \overrightarrow {OA} $$ $$\overrightarrow {AB} = \left( {{a_2} - {a_1}} \right)\widehat i + \left( {{b_2} - {b_1}} \right)\widehat j + \left( {{c_2} - {c_1}} \right)\widehat k$$
Similarly, $$\overrightarrow {BA} = \overrightarrow {OA} - \overrightarrow {OB} $$
Distance between point $A$ and $B$ is given by, $$\left| {\overrightarrow {AB} } \right| = \sqrt {{{\left( {{a_2} - {a_1}} \right)}^2} + {{\left( {{b_2} - {b_1}} \right)}^2} + {{\left( {{c_2} - {c_1}} \right)}^2}} $$

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