$A$ convex mirror of focal length $20 \, cm$ is fitted in a car. $A$ second car,which is $2.8 \, m$ away,overtakes the first car at a relative speed of $15 \, m/s$. What will be the speed of the second car as observed in the mirror of the first car?

An object is at a distance of $20\,m$ from a convex lens of focal length $0.3\,m$. The lens forms an image of the object. If the object moves away from the lens at a speed of $5\,m/s$,the speed and direction of the image will be

There are two plane mirrors with reflecting surfaces facing each other. The mirrors are moving with speed $v$ away from each other. $A$ point object is placed between the mirrors. The velocity of the $n$-th image will be

If an object and a plane mirror both move towards each other with a velocity of $v$,what is the velocity of the image?

$A$ luminous point object is moving along the principal axis of a concave mirror of focal length $12 \ cm$ towards it. When its distance from the mirror is $20 \ cm$,its velocity is $4 \ cm/s$. The velocity of the image in $cm/s$ at that instant is:

$A$ point object is moving uniformly towards the pole of a concave mirror of focal length $25 \ cm$ along its axis as shown below. The speed of the object is $1 \ ms^{-1}$. At $t=0$,the distance of the object from the mirror is $50 \ cm$. The average velocity of the image formed by the mirror between time $t=0$ and $t=0.25 \ s$ is