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Question: Answered & Verified by Expert
A car is moving with at a constant speed of $60 \mathrm{~km} \mathrm{~h}^{-1}$ on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of $100 \mathrm{~m}$ and is approaching with a speed of 5 $\mathrm{kmh}^{-1}$.
In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car after every $2 \mathrm{~s}$ till the other car overtakes. If the two cars were maintaining their speeds, which of the following statement (s) is/are correct?
PhysicsRay Optics
Options:
  • A
    The speed of the car in the rear is $65 \mathrm{~km} \mathrm{~h}^{-1}$
  • B
    In the side mirror, the car in the rear would appear to approach with a speed of $5 \mathrm{kmh}^{-1}$ to the driver of the leading car
  • C
    In the rear view mirror, the speed of the approaching car would appear to decrease as the distance between the cars decreases
  • D
    In the side mirror, the speed of the approaching car would appear to increase as the distance between the cars decreases
Solution:
1060 Upvotes Verified Answer
The correct answer is:
In the side mirror, the speed of the approaching car would appear to increase as the distance between the cars decreases
As we know that, the image formed by convex mirror does not depend on the relative position of object w.r.t. mirror.
So, when the car approaches in the rear side, initially it appear at rest as images is formed at focus. Hence the speed of the image of the car would appear to increase as the distance between the cars decreases.

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