An object (O) and a plane mirror (M) are placed in the positions as shown in the figure. If the object and the mirror moves simultaneously towards right in a straight path at uniform speed of 2cms−1 and 5cms−1 respectively, find the shift in the image of the object at the end of 10 seconds :
The effective speed with which the mirror will move away from the object will be 5−2=3 cm/s
Hence, after 10s, mirror will be 30 cm away from object. The mirror will be 50 cm from its original position and the object 20 cm.
The original image was formed 40 cm on the right of the mirror. The new image will be formed 40+30=70 cm on the right of the new position of the mirror
If O is origin,
Original position of object=0
Original position of mirror= 40
Original position of image= 80
New position of object= 20
New position of mirror= 90
New position of mage= 160
Hence, shift in image= 160−80=80 cm