A train crosses a platform 100 m long in 60 seconds at a speed of 45 kmph. The time taken by the train to cross an electric pole is
Answer & explanation
Correct answer: option 2
Speed = \(\frac{ Distance}{ Time}\)
Let the length of the train be x
45 x \(\frac{ 5}{18 }\) = \(\frac{\text{100 + x}}{ 60}\)
5 x \(\frac{ 5}{2 }\) = \(\frac{\text{100 + x}}{ 60}\)
\(\frac{ 25}{2 }\) = \(\frac{\text{100 + x}}{ 60}\)
60 x 25 = 2(100 + x)
1500 = 200 + 2x
2x = 1300
x = 650
The length of the train is 650 m
Time = \(\frac{ Distance}{Speed}\)
Time = \(\frac{ 650}{25/2}\)
Time = \(\frac{1300}{25}\)
Time = 52 seconds