A boy reaches the airport and find that the escalator is not working. He walks up the stationary escalator in time t1. If he remains stationary on a moving escalator then the escalator takes him up in time t2. The time taken by him to walk up on the moving escalator will be:

Let the distance travelled is x, so | v → E g | = x t 2 ⇒ speed of escalator for ground | v → B E | = x t 1 ⇒ speed of boy concerning the escalator | v → B g | = x t 1 + x t 2 ⇒ speed of boy concerning groundThe time taken by him to walk up the moving escalator = t = x | v → B g | ⇒ t = x x t 1 + x t 2 = t 1 t 2 t 1 + t 2

A boy reaches the airport and find that the escalator is not working. He walks up the stationary escalator in time t1. If he remains stationary on a moving escalator then the escalator takes him up in time t2. The time taken by him to walk up on the moving escalator will be:

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Physics Motion in Straight Line Physics Class 11th Motion in a Straight Line

A boy reaches the airport and find that the escalator is not working. He walks up the stationary escalator in time t₁. If he remains stationary on a moving escalator then the escalator takes him up in time t₂. The time taken by him to walk up on the moving escalator will be:

Option 1 -

$\frac{t_{1} t_{2}}{t_{2} + t_{1}}$

Option 2 -

$t_{2} - t_{1}$

Option 3 -

$\frac{t_{1} + t_{2}}{2}$

Option 4 -

$\frac{t_{1} t_{2}}{t_{2} - t_{1}}$

2 Views | Posted a month ago

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1 Answer

Answered by

Vishal Baghel | Contributor-Level 10

a month ago

Correct Option - 1

Detailed Solution:

Let the distance travelled is x, so

$| {\vec{v}}_{E g} | = \frac{x}{t_{2}} \Rightarrow$ speed of escalator for ground

$| {\vec{v}}_{B E} | = \frac{x}{t_{1}} \Rightarrow$ speed of boy concerning the escalator

$| {\vec{v}}_{B g} | = \frac{x}{t_{1}} + \frac{x}{t_{2}} \Rightarrow$ speed of boy concerning ground

The time taken by him to walk up the moving escalator = t = $\frac{x}{| {\vec{v}}_{B g} |}$ $\frac{}{_{}}$

$\Rightarrow t = \frac{x}{\frac{x}{t_{1}} + \frac{x}{t_{2}}} = \frac{t_{1} t_{2}}{t_{1} + t_{2}}$

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A boy reaches the airport and find that the escalator is not working. He walks up the stationary escalator in time t₁. If he remains stationary on a moving escalator then the escalator takes him up in time t₂. The time taken by him to walk up on the moving escalator will be:

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