Question

A plane mirror is kept parallel to $y$-axis. A point object is approaching the mirror with velocity $\vec{u}=(10\hat{i}+10\hat{j})m/s$. The magnitude of relative velocity of objective w.r.t image is equal to

• A. $20\sqrt{2}m/s$
• B. $20m/s$
• C. $10\sqrt{2}m/s$
• D. $10m/s$

Answer 1

Answer: (B)

Velocity of image in mirror
$\vec{v}=-10\hat{i}+10\hat{j}$
${\vec{v}}_{\text{rel }}=\vec{u}-\vec{v}=20\hat{i}$