Question

The distances \(u\) and \(v\) of an object and its image respectively from a lens of focal length \(f\) are connected by the formula \[\begin{equation*} \frac{1}{u} + \frac{1}{v} = \frac{1}{f}. \end{equation*}\]

Determine the speed of the image of an object when the object is \(\quantity{3}{m}\) from a lens of focal length \(\quantity{\dfrac{1}{2}}{m}\) and is moving away from the lens at \(\quantity{5}{m\,s^{-1}}\).