A train, $140$ metres long, moves at the rate of $36\,\mathrm{kmph}$. How long will it take to pass a certain telegraph pole?
A$10$ sec
B$12$ sec
C$14$ sec
D$18$ sec
Answer & Solution
Correct answer: C. $14$ sec
To pass a pole, the train must cover its own length only. Convert $36\,\mathrm{kmph}$ to m/s: $36\times \frac{5}{18}=10\,\mathrm{m/s}$. Therefore time $=\frac{140}{10}=14$ seconds. The height of the pole does not matter.
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