First slide

Rectilinear Motion

Question

A person walks up a stalled $15 m$ long escalator in $90 s$ . When standing on the same escalator now moving, the person is carried up in $60 s$ . How much time would it take that person to walk up the moving escalator? . Does the answer depend on the length of the escalator?

Moderate

A

45 s
B

55 s
C

58 s
D

36 s

Solution

$v_{1} = speed of person v_{2} = speed of escalator v_{1} = \frac{1}{t_{1}} and v_{2} = \frac{1}{t_{2}} ∴ t = \frac{1}{v_{1} + v_{2}} = \frac{1}{\frac{1}{t_{1}} + \frac{1}{t_{2}}} = \frac{t_{1} t_{2}}{t_{1} + t_{2}} = \frac{90 \times 60}{90 + 60} = 36 s$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App