Object O is placed in front of a plane mirror M. A glass slab S having thickness t = 3 cm and refractive index `mu = 1.8` is placed between the object and the mirror. The refracting faces of the slab are parallel to the mirror surface. The object is made to move with a velocity of `u = 2 m//s` perpendicular to the mirror surface. Find the speed of the image formed after
(a) refraction from the slab followed by reflection from the mirror.
(b) refraction from the slab followed by reflection from the mirror followed by the refraction from the slab.
