Verified Solution • 2025–26 Session moderate

QJEEM20Phb116: JEE Main 2020 Physics - Class 11 JEEM20Phb116 Solution: Train A and train B are running on parallel tracks in the…

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)

Multiple Choice Options

  • A 30.5 ms–1
  • B 29.5 ms–1
  • C 31.5 ms–1
  • D 28.5 ms–1

Step-by-Step Verified Solution

Velocity of man with respect to ground

V→m/g{\overrightarrow V _{m/g}} = V→m/A{\overrightarrow V _{m/A}} + V→A{\overrightarrow V _{A}}

= -1.8 + 36

Velocity of man w.r.t. B

V→m/B{\overrightarrow V _{m/B}} = V→m{\overrightarrow V _{m}} - V→B{\overrightarrow V _{B}}

= –1.8 + 36 – (–72)

= 106.2 km/hr

= 29.5 m/s

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