A 200 m long train is moving at a speed of 80 km/h. In what time will it cross a single pole?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 9 sec
To cross a pole, the train must cover its own length, since the pole has no length of its own. Change the speed to metres per second first, because the length is in metres.
Speed \(\displaystyle =80\times\frac{5}{18}=\frac{200}{9}\) m/s
Time \(\displaystyle =\frac{200}{200/9}=9\) s
Tip: To change km/h to m/s, multiply by \(\frac{5}{18}\) (1000 m in 3600 s); to change m/s to km/h, multiply by \(\frac{18}{5}\).