A point object is at rest on the principal axis at a distance of 20 cm from a concave mirror of radius of curvature 30 cm. Under the action of a horizontal force, the object moves away from the mirror along the axis and reaches a distance of 40 cm from the mirror in a time of 3 s. The acceleration of the image is:
Show Hint
For moving object–mirror problems, write \(v\) in terms of \(u\) and differentiate with respect to time.