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NEET 2017 · Relative Velocity

Relative Velocity question from NEET 2017

Q10NEET 2017Medium

Relative Velocity

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t1. On another day, if she remains stationary on the moving escalator, then the escalator takes her up in time t2. The time taken by her to walk up on the moving escalator will be

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Answer: (b)

  1. Length LL: her speed Lt1\frac{L}{t_1}, escalator speed Lt2\frac{L}{t_2}
  2. Walking on moving escalator: t=LL/t1+L/t2t = \frac{L}{L/t_1 + L/t_2}
  3. t=t1t2t1+t2t = \frac{t_1t_2}{t_1 + t_2}, so the answer is (b).
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