Correct Answer - Option 3 : 33 sec
GIVEN:
The slower train is twice the faster train in length.
Speed of faster train = 90 km/h
Speed of slower train = 60 km/h
Time taken to overtake = 45 sec
Length of bridge = 300 m
FORMULA USED:
Relative speed in same direction = faster speed - slower speed
Distance = \( {speed}\times{time}\)
\(\frac{km}h\times\frac5{18}=\frac {m}{s}\)
EXPLANATION:
Let the length of the faster train be 'X' m and that of the slower train is '2X' m.
Total distance traveled in overtaking is equal to the sum of the lengths of both trains at relative speed.
Relative speed = 90 - 60 = 30 km/h
Distance 3X = \(30\times\frac{5}{18}\times45\) = 375 m
X (length of faster train) = 125 m
2X (length of slower tain) = 250 m
Distance traveled by train to cross a bridge = length of train + length of bridge
\(\Rightarrow\) D = 250 + 300 = 550 m
Time = \(\frac{550\times 18}{60\times5}=33 sec\)