On a 60km track travels the first 30km with a uniform speed of 30km/h. How fast must the train travel the next 30km so as to average 40km.h for the entire trip?

On a 60km track travels the first 30km with a uniform speed of 30km/h. How fast must the train travel the next 30km so as to average 40km.h for the entire trip? Correct Answer 60km.h

vav = (2v1 v2)/(v1+v2) 40 = (2×30×v2)/(30+v2) v2 = 60km/h.
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