The rear view mirror of a car is a plane mirror.A driver is reversing his car at a speed of 2m/s.The driver sees in his rear view mirror the image of the truck parked behind the car.The speed at which the image of the truck appear to approach the driver will be ?

In this case the mirror is on move with the driver so the image should come closer by the same distance moved by the car but so is not the case as mentioned in my textbook.



  • $\begingroup$ You might want to include the statement from your text. $\endgroup$
    – R.W. Bird
    Nov 8, 2019 at 19:24

1 Answer 1


The image is initially in front of the driver - that is where it appears when the driver looks in the mirror.

You are right - the image gets closer to the driver by 2m/sec.

But the driver is moving backwards at 2m/sec.

As far as the world outside is concerned the image moves backwards at 4m/sec.

  • $\begingroup$ Shouldn't it be that the image approaches the object at the speed of 4 m/s and not the driver? $\endgroup$ Jan 17, 2020 at 3:17
  • $\begingroup$ Yes, that is what happens, and you explain it well, but the question was about the driver. $\endgroup$
    – DrC
    Jan 18, 2020 at 10:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.