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 $V _{ i }=2 V _{ m }- V _{ o }$.
$V _{ i }= o .$ in $x$ direction.
so $V_{ i }=-3 \hat{ i }+4 \hat{ k }$.