Question

A plane mirror is placed along the x -axis facing negative y -axis. The mirror is fixed. A point object is moving with $(3 \hat{i}+4 \hat{j})$ in front of the plane mirror. The relative velocity of image with respect to its object is

• A. $-8 \hat{j}$
• B. $8 \hat{j}$
• C. $3 \hat{i}-4 \hat{j}$
• D. $-6 \hat{i}$

Answer 1

Answer: (A)

Velocity of object,
$\vec{v}_{ ob }=3 \hat{i}+4 \hat{j}$
Velocity of image,
$\vec{v}_{\text {image }}=3 \hat{i}-4 \hat{j}$
Relative velocity of image with respect to its object
$\vec{v}_{\text {rel }}=\vec{v}_{\text {image }}-\vec{v}_{\text {ob }}=(3 \hat{i}-4 \hat{j})-(3 \hat{i}+4 \hat{j})=-8 \hat{j}$