Image of an object approaching a convex mirror of radius of curvature 20 m along its optical axis is observed to move from in 30 seconds. What is the speed of the object in km per hour?

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Physics

Spherical Mirror New

Question

Image of an object approaching a convex mirror of radius of curvature 20 m along its optical axis is observed to move from $\frac{25}{3} m to \frac{50}{7} m$ in 30 seconds. What is the speed of the object in km per hour?

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$v = \frac{25}{3}$

$\frac{1}{v} + \frac{3}{25} = \frac{1}{10}$

$\frac{1}{v} = \frac{1}{10} - \frac{3}{25} = \frac{25 - 30}{250} = \frac{- 5}{250}$

u₂ = – 50

$\frac{1}{v} + \frac{7}{50} = \frac{1}{10} = \frac{1}{v} = \frac{1}{10} - \frac{7}{50} = \frac{5 - 7}{50} = - 25$

$vel . obj . = \frac{25}{30} m / s = \frac{25}{30} \times \frac{18}{5} = 3 km / hr$