JEE Main 2014 · 12 Apr · Shift 1 · Physics Q2

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PhysicsSingle correct+4 / -1Question 2 of 90

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

37 s

27 s

24 s

45 s

Answer and worked solution

Official answer: C

Let the escalator length be $L$ . Walking speed $\frac L{60}$ , escalator speed $\frac L{40}$ . Together:
$t=\frac L{L/60+L/40}=\frac{1}{\frac1{60}+\frac1{40}}=24\text{ s}.$

Topics:Relative velocity

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JEE Main 2014 · 12 Apr · Shift 1, Physics question 2