Question

A person climbs up a stopped escalator in $60s$. If standing on the same escalator but escalator running with constant velocity, he takes 40 s. How much time is taken by the person to walk up in the moving escalator?

• A. $37s$
• B. $27s$
• C. $24s$
• D. $45s$

Answer 1

Answer: (C)

$24s$

Let the length of the escalator be $L$
The rest velocity of the man be, $u$
The velocity of escalator be $v$
So, $L=60u$ and Also, $L=40v$
Let, $t$ be the time taken to move up the escalator.
The total velocity will be, $u+v$
So time taken = $\frac{L}{u+v}$
Now, u = $\frac{L}{60}$ and v = $\frac{L}{40}$
Substituting the value, $t=24sec$