Question
Two trains βT5β and βU5β of lengths 800 metres
and 400 metres respectively are travelling towards each other. Ratio of speed of βT5β to βU5β is 5:3. If the trains take 60 seconds to cross each other from the time they meet, then find the average of speeds (in km/h) of trains βT5β and βU5β.Solution
Let the speeds be 5y and 3y m/s respectively.
Relative speed = 5y + 3y = 8y m/s
ATQ,
8y Γ 60 = 800 + 400
β 480y = 1200
β y = 2.5
Therefore, required average = (5y + 3y) Γ· 2 = 4y
= 4 Γ 2.5 = 10 m/s = 10 Γ (18/5) = 36 km/h
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