1. The problem statement, all variables and given/known data The rear view mirror of a car is a plane mirror. A driver is reversing his car at the speed of 2 m/s. The driver sees in his rear view mirror the image of a truck parked behind hid car. The speed at which the image of the truck appears to approach the driver will be? 3. The attempt at a solution Well my answer is 2 m/s but this is an example question so the solution accompanies the question and their answer is 4 m/s. The explanation they have provided is "In a plane mirror, the object and it's image always remain at the same distance from the mirror, So. when the car reverses at a speed of 2 m/s, the the image will also appear to move towards the mirror at the same speed of 2 m/s. So the speed at which the image of the truck appears to approach the car driver will be 2+2=4 m/s." What? Everything till the last line makes sense. I tried this on paper and the image does actually move at 4 m/s relative to the truck but relative to the driver it moves only 2 m/s as the driver is moving away from the image at a rate of 2 m/s which cancels 2 m/s from the speed of the image, creating an effective speed of 2 m/s. Who's right and who's wrong?