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the rear view mirror of a car is a plane mirror a...

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

(i) 1 m/s (ii) 2 m/s
(iii) 4 m/s (iv) 8 m/s

Answer:

(iii) 4 m/s

The car is approaching the truck with the speed of 2 m/s which shows by the speed of the car 2 m/s. The distance between both of them decreases by double. This is because the truck's image will travel a distance twice the distance covered by the car in same time. Hence, the image of the truck will appear to approach the driver with the speed of: 2 m/s + 2 m/s = 4 m/s.

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