Correct Answer - Option 1 : 31 second
Given:
The length of train = 153 m
The length of bridge = 622 m
Speed of train = 90 km/h
Formula used:
S = D/T
Where,
S = Speed
D = Total distance
T = Time
Calculation:
According to the question:
Total distance = length of train + length of bridge
⇒ D = 153 + 622
⇒ D = 775 m
S = 90 km/h
⇒ S = 90 × (5/18) m/s
⇒ S = 25 m/s
Now,
S = D/T
⇒ 25 = 775/T
⇒ T = 775/25
⇒ T = 31 second
∴ The time taken by train to cross the bridge is 31 second.
1) 1 km/h = (5/18) m/s
2) 1 m/s = (18/5) km/h