Reflection by Spherical Mirrors: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Reflection by Spherical Mirrors. Understanding the underlying formula is key to arriving at the correct answer below:

Using the relation between object and image velocity: \(v_i = -m^2 v_o\). Here, magnification \(m = \frac{f}{f-u} =\frac{-25}{-25 - (-20)} = 5\). Hence, \(v_i = -5^2 \times 5 = -125\text{ cm/s}\). The speed is \(125\text{ cm/s}\).