Question

On Indira Gandhi international airport, a girl walks on stationary walkaway for 12 seconds, then on moving walkaway she covers same distance without walking in 6 seconds. Now if she walks on moving walkaway, in what time will she cover the same distance?

• A. 18 s
• B. 9 s
• C. 3 s
• D. 4 s

Answer 1

The correct option is D 4 s

$t_1=\frac{x}{v_1}$ (stationary walk away)
$t_2=\frac{x}{v_2}$ (rest on moving walkaway)
$t_3=\frac{x}{v_1+v_2}=\frac{x}{\frac{x}{t_1}+\frac{x}{t_2}}=\frac{t_1{t}_2}{t_1+t_2}=\frac{12\times 6}{18}=\frac{72}{18}$
$=4$ s