Q. The position vector of midpoint lying on the line joining the points whose position vectors are $\widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}}$ and $\widehat{\dot{\mathbf{i}}} - \widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}},$ is
A) $\widehat{\dot{\mathbf{j}}}$
B) $\widehat{\dot{\mathbf{i}}}$
C) $\widehat{\mathbf{k}}$
D) $\overrightarrow{\mathbf{0}}$
Explanation
(b)
The position vector of midpoint of line joining the points whose position vector are $\widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}}$ and $\widehat{\dot{\mathbf{i}}} - \widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}}$
$= \frac{\widehat{\dot{\mathbf{i}}} + \widehat{\dot{\mathbf{j}}} - \widehat{\mathbf{k}} + \widehat{\dot{\mathbf{i}}} - \widehat{\dot{\mathbf{j}}} + \widehat{\mathbf{k}}}{2} = \widehat{\dot{\mathbf{i}}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.