Question

A plane mirror is placed at the origin parallel to $y-$ axis, facing the positive $x-$ axis. An object starts from $(2m,0,0)$ with a velocity of $(2\hat{i}+2\hat{j})\text{m/s}$. The relative velocity of image with respect to object is along

• A. positive $x-$ axis
• B. negative $x-$ axis
• C. positive $y-$ axis
• D. negative $y-$ axis

Answer 1

The correct option is B negative $x-$ axis

${\overrightarrow{v}}_o=2\hat{i}+2\hat{j}$
Thus, the velocity of image will be,
${\overrightarrow{v}}_i=-2\hat{i}+2\hat{j}$

Relative velocity $\overrightarrow{v}={\overrightarrow{v}}_i-{\overrightarrow{v}}_o=-2\hat{i}+2\hat{j}-2\hat{i}-2\hat{j}$
$\Rightarrow \overrightarrow{v}=-4\hat{i}$

Relative velocity of image with respect to object is in negative $x-$direction as shown in figure.



Hence, the correct answer is option (b).