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JEE Main20202 Sep 2020Morning ShiftPhysicsMotion in One DimensionActual

Train A and train B are running on parallel tracks in the opposite directions with speed of 36 km hour - 1 and 72 km hour - 1 , respectively. A person is walking in train A in the direction opposite to its motion with a speed of 1 . 8 km hour - 1 . Speed in m s - 1 of this person as observed from train B will be close to: (take the distance between the tracks as negligible)

Options

  1. A29 . 5   m   s - 1
  2. B28 . 5   m   s - 1
  3. C31 . 5   m   s - 1
  4. D30 . 5   m   s - 1

Correct answer

A. 29 . 5   m   s - 1

Step-by-step solution

V M A = - 1 . 8 km   hr - 1 = - 0 . 5   m   s - 1 V man , B = V man , A + V A , B = V man , A + V A - V B = - 0 . 5 + 10 - ( - 20 ) = - 0 . 5 + 30 = 29 . 5   m   s - 1

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