A particle is moving at a constant speed V from a large distance towards a concave mirror of radius R along its principal axis. Find the speed of the image formed by the mirror as a function of the distance x of the particle from the mirror.
given
Radius of the concave mirror= R
Focal length of the mirror, 
Velocity of the particle, 
Let velocity of the image is represented as V’
The distance of the object from the mirror, u= -x
Using mirror equation,
1