A boy reaches the airport and finds that the escalator is not working. He walks up the stationary escalator…

A boy reaches the airport and finds that the escalator is not working. He walks up the stationary escalator in time t1. If he remains stationary on a moving escalator then the escalator takes him up in time t2. The time taken by him to walk up on the moving escalator will be:

  1. t1t2t2-t1
  2. t1+t22
  3. t1t2t2+t1
  4. t2-t1

Solution

L= Length of escalator

Vb/ecc=Lt1

When only escalator is moving, 

Vesc=Lt2

when both are moving, 

Vb/g=Vb/esc+Vesc

Vb/g=Lt1+Lt2t=LVb/g=t1t2t1+t2

Asked in: JEE Main 2021 (20 Jul Shift 2)

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