# Mirror in the arrangement shown in figure is moving up with speed 4 centimetre per second.  Find the speed of final image of object O formed after two refraction and one reflection.

Md Mushahid
21 Points
3 years ago
refer the fig

apparent distance of mirror from 0 and mirror =$x+\frac{y}{\mu }$

distance between o and image = $2\left (x+\frac{y}{\mu } \right )$

$v =\frac{d\left ( distance \right )}{dt}$

$v =2\left ( \frac{dx}{dt} +\frac{1}{\mu }\frac{dy}{dx} \right )$
$v =2\left ( 0 +\frac{1}{\frac{4}{3}}\times 8\right )$
$v =2\left ( \frac{3}{4}\times 8\right )$
$v = 12 \frac{cm}{sec}$
the speed of final image of object O formed after two refraction and one reflection is 12cm/sec