Question

A point object is moving with velocity ${\text{v}}_0=2\hat{\text{i}}-3\hat{\text{j}}+4\hat{\text{k}}$ in front of a moving plane mirror whose normal is along x - axis. The mirror is moving with velocity ${\text{v}}_{\text{m}}=\hat{\text{i}}-4\hat{\text{j}}+2\hat{\text{k}}$ . Find the velocity vector of image.

• A. $-5\hat{\text{j}}$
• B. $-3\hat{\text{j}}+4\hat{\text{k}}$
• C. $-4\hat{\text{j}}+2\hat{\text{k}}$
• D. $2\hat{\text{i}}-3\hat{\text{j}}+2\hat{\text{k}}$

Answer 1

Answer: (B)

As $x$-axis is the normal to the mirror.
so, only $x$ component will change and $y,z$ component will remain same.
in $x$ directions $V_i=2V_m-V_o$.
$V_i=o.$ in $x$ direction.
so $V_i=-3\hat{i}+4\hat{k}$.