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JEE Main 202313 AprilEvening Shift
Exam
JEE Main
Year
2023
Date
13 April
Shift
Evening Shift
Subject
Physics
Chapter
Motion in One Dimension

JEE Main 2023 · 13 April · Evening Shift · Physics · Motion in One Dimension

A passenger sitting in a train A moving at 90km h ^ - 1 observes...

A passenger sitting in a train A moving at 90kmh−190km{h}^{- 1} observes another train B moving in the opposite direction for 8s8s. If the velocity of the train B is 54kmh−154km{h}^{- 1}, then length of train B is:

Options

  1. A120m120m
  2. B320m320m
  3. C80m80m
  4. D200m200m

Correct answer

B. 320m320m

Step-by-step solution

Let the velocity of A be vA{v}_{A} and the velocity of B be vB{v}_{B}.

The relative velocity is

v→BA=v→B−v→A⇒vBA=54−(−90)=144kmh−1\overset{\to}{v}BA = \overset{\to}{v}B - \overset{\to}{v}A ⇒ {v}_{BA} = 54 - ( - 90 ) = 144km{h}^{- 1}

⇒vBA=40ms−1⇒ {v}_{BA} = 40m{s}^{- 1}

Time = \dfrac{length}{{v}_{BA}}</p><p></p><p>⇒ length = 40m{s}^{- 1} \times 8s = 320m

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