Question

A cubical room is formed with six plane mirrors. An insect moves along the diagonal of the floor with uniform speed. The velocities of its image in two adjacent walls are $20\sqrt{2}$ cm/s. Then the velocity in cm/s of the image formed by roof is?

Answer 1

It is the resultant of two velocities because two adjacent mirrors shows vertical component of velocities.

So velocity (V) in ceiling will be the actual velocity

$V=\sqrt{{10}^2+{10}^2}$

$=\sqrt{2\times {10}^2}$

$=\sqrt[10]{102}\frac{cm}{s}$