A luminous point object is moving along the principal axis of a concave mirror of…

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

A luminous point object is moving along the principal axis of a concave mirror of focal length

12\,\mathrm{cm}

towards it. When its distance from the mirror is

20\,\mathrm{cm}

, its velocity is

4\,\mathrm{cm\,s^{-1}}

. The velocity of the image at that instant is (1)

6\,\mathrm{cm\,s^{-1}}

, towards the mirror (2)

6\,\mathrm{cm\,s^{-1}}

, away from the mirror (3)

9\,\mathrm{cm\,s^{-1}}

, away from the mirror (4)

9\,\mathrm{cm\,s^{-1}}

, towards the mirror