A plane mirror is moving with velocity $4\hat{\mathrm{i}}+5\hat{\mathrm{j}}+8\hat{\mathrm{k}}$. A point object in front of the mirror moves with a velocity $3\hat{\mathrm{i}}+4\hat{\mathrm{j}}+5\hat{\mathrm{k}}$. Here $\hat{\mathrm{k}}$ is along the normal to the plane mirror and facing towards the object. The velocity of the image is:

A square $ABCD\mathit{ }$of side $1 \mathrm{mm}$ is kept at distance $15 \mathrm{cm}$ infront of the concave mirror as shown in the figure. The focal length of the mirror is $10 \mathrm{cm}$. The length of the perimeter of its image will be (nearly):

In the figure shown find the total magnification after two successive reflections first on$M_1$ and then on $M_2$.