If a 180 metre long train crosses a pole in 9 seconds, find the speed of the train in kilometre/hour.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 72 km/h
To cross a pole, the train must move its own length, because the pole has no length of its own. Speed is distance divided by time, and 1 m/s \(=\frac{18}{5}\) km/h (since 1 m/s is 3600 m in an hour, that is, 3.6 km/h).
Speed \(\displaystyle =\frac{180}{9}=20\) m/s
In km/h: \(\displaystyle 20\times\frac{18}{5}=72\) km/h