Easy MCQ +4 / -1 PYQ · JEE Mains 2020

Train A and train B are running on parallel tracks in the opposite directions with speeds of 36 km/hour and 72 km/hour, respectively. A person is walking in train A in the direction opposite to its motion with a speed of 1.8 km/ hour. Speed (in ms–1) of this person as observed from train B will be close to :
(take the distance between the tracks as negligible)

  1. A 30.5 ms<sup>–1</sup>
  2. B 29.5 ms<sup>–1</sup> Correct answer
  3. C 31.5 ms<sup>–1</sup>
  4. D 28.5 ms<sup>–1</sup>

Solution

Velocity of man with respect to ground <br><br>${\overrightarrow V _{m/g}}$ = ${\overrightarrow V _{m/A}}$ + ${\overrightarrow V _{A}}$ <br><br>= -1.8 + 36 <br><br>Velocity of man w.r.t. B <br><br>${\overrightarrow V _{m/B}}$ = ${\overrightarrow V _{m}}$ - ${\overrightarrow V _{B}}$ <br><br>= –1.8 + 36 – (–72) <br><br>= 106.2 km/hr <br><br>= 29.5 m/s

About this question

Subject: Physics · Chapter: Kinematics · Topic: Motion in a Straight Line

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