A person walks up a stalled escalator in 90 s . When standing on the same moving escalator he reached in 60…

A person walks up a stalled escalator in 90 s . When standing on the same moving escalator he reached in 60 s . The time it would take him to walk up the moving escalator will be.
  1. 36 s
  2. 72 s
  3. 18 s
  4. 27 s

Solution

$\begin{aligned} & t_1=\frac{1}{v_m}, t_2=\frac{1}{v_s} \\ & t_3=\frac{1}{v_m+v_s}=\frac{1}{\frac{1}{t_1}+\frac{1}{t_2}}=\frac{t_1 t_2}{t_1+t_2}=\frac{90 \times 60}{90+60}=36 \mathrm{~s}\end{aligned}$

Asked in: AP EAMCET 2024 (23 May Shift 1)

Practice more Motion In One Dimension questions on Aicharya