Question
Tue September 27, 2011 By: Aditi Pandey

The driver of a blue car moving at a speed of 80km/hr suddenly realises that she is about to rear-end a red car moving at a speed of 60 km/hr. To avoid a collision what is the maximum speed the blue car can have just as it reaches the red car?

Expert Reply
Fri September 30, 2011

peed of the car moving ahead = 60 km/hr

Speed of the car moving behind = 80 km/hr

Let the speed required of the car moving behind at the time it reaches the car moving ahead be x km/hr

Now the relative velocity of the car moving behind wrt the car moving ahead shud not be positive.

hence ..

x - 60 <= 0 

x <= 60

as the question asks for the maximum value of x ..

hence ..answer is 60 km/hr.

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