Physics - Geometrical Optics Question with Solution | TestHub

An object and a concave mirror of focal length $\mathrm{f}=10\mathrm{cm}$ both move along the principal axis of the mirror with constant speeds. The object moves with speed ${\mathrm{V}}_0=6\mathrm{cm}{\mathrm{s}}^{-1}$ towards the mirror with respect to a laboratory frame. The distance between the object and the mirror at a given moment is denoted by u . When $\mathrm{u}=20\mathrm{cm}$, the speed of the mirror ${\mathrm{V}}_{\mathrm{m}}$ is such that the image is instantaneously at rest with respect to the laboratory frame, and the object forms a real image. The magnitude of ${\mathrm{V}}_{\mathrm{m}}$ is $\_\_\_\_$ $\mathrm{cm}{\mathrm{s}}^{-1}$.