A train running at a speed of 45 km/h crosses a 100 m long platform in 60 seconds. The time taken by the train to cross an electric pole is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 52 seconds
To cross a platform, a train covers its own length plus the platform’s length; to pass a pole it covers only its own length. So the train’s length is found first.
Speed \(=45\times\frac{5}{18}=12.5\) m/s
Distance covered in 60 s \(=12.5\times60=750\) m
Length of the train \(=750-100=650\) m
Time to pass the pole \(\displaystyle=\frac{650}{12.5}=52\) s
Shortcut: The pole saves the train the 100 m of the platform, which takes \(\frac{100}{12.5}=8\) s at its speed, so it passes the pole in \(60-8=52\) s.