When a man stands on a moving escalator he goes up in 50sec. and when he walks up the moving escalator he goes up in 30sec. Then the man walks up the stationary escalator in a time of −−−−sec
A
60
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B
75
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C
90
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D
18.75
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Solution
The correct option is B75
Suppose the escalator is x meter long.
When man stand then his net velocity will be only that of escalator i.e. ve so x=ve×50 .....(1)
When the man walks on the escalator then the net velocity will be sum of both i.e ve+vm so x=(ve+vm)×30 .....(2)
If the man only walks and the escalator is stationary then the net velocity is vm so time being t give us x=vm×t .....(3)
Equation-1 substraced from equation-2 we get 20ve=30vm
putting it in equation-1 and put x=50ve in eqaution-3
we will get x=2t×ve3, comparing it with eqaution-1