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Write to us for help in understanding the solution. Solutions/Answers to NCERT/ CBSE PHYSICS Class 11(Class XI)textbook. Exercise and Additional exercise.
NCERT/CBSE PHYSICS CLASS 11 textbook http://www.TutorBreeze.com Contact for Online Tutoring in Physics, Math, Chemistry, English Solutions/Answers to NCERT/CBSE PHYSICS Class 11(Class XI)textbook Exercise and Additional exercise CHAPTER THREE MOTION IN A STRAIGHT LINE EXERCISES 3.8 On a two-lane road, car A is travelling with a speed of 36 km h–1. Two cars B and C approach car A in opposite directions with a speed of 54 km h–1 each. At a certain instant, when the distance AB is equal to AC, both being 1 km, B decides to overtake A before C does. What minimum acceleration of car B is required to avoid an accident ?

Q. 3.8 Two lane road Speed of Car A = 6 km/hr = 10 m/s Speed of car B (VB

) = 54 km/r = 15 m/s

Speed of car C (VC

) = 54 km/r = 15 m/s

Relative speed of Car B wrt Ai.e., VBA = VB − VA = 15 − 10 = 5m/s Relative speed of Car C, w.r.t. A

i.e.,

VCA = VC − ( −VA ) = VC + VA = 15 + 10 = 25m / s AB = AC = 1 km =1000 m. S = ut

t=

A S 1000 = C = = 40s u VCA 25

Let A = acceleration of car B for t = 40 s S = ut +

1 2 at 2

AB = uBA t +

1 2 at 2

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NCERT/CBSE PHYSICS CLASS 11 textbook http://www.TutorBreeze.com

1000 = 5 × 40 +

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1 2 × a × ( 40 ) 2

a = 1m / s 2

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