Train A and train B are running on parallel tracks in the opposite directions with speed of 36   km…

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) 
  1. 29.5 m s-1
  2. 28.5 m s-1
  3. 31.5 m s-1
  4. 30.5 m s-1

Solution

VMA=-1.8km hr-1=-0.5 m s-1

Vman,B=Vman,A+VA,B

=Vman,A+VA-VB

=-0.5+10-(-20)

=-0.5+30

=29.5 m s-1

Asked in: JEE Main 2020 (02 Sep Shift 1)

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