A train 300 m long is running with a speed of 54 km/hr. In what time it cross a telephone pole ?

Answer: Option A

Here length of pole is considered 0 metre
Time will be taken by train to cross the poll :
$$\begin{array}{rl}& =\frac{\text{300 m}}{54\times \frac{5}{18}\text{ m/s}}\\ & =\frac{300}{15}\\ & =20\end{array}$$
Required time = 20 seconds