A train is running with a speed of $79.2\text{km/hr}$ and it crosses a pole in $7\text{sec}$. Then find the length of the train.

Given:
* Speed of the train = $79.2\text{km/hr}$
* Time taken to cross the pole = $7\text{sec}$

First, convert the speed from $\text{km/hr}$ to $\text{m/s}$:

$$\text{Speed}=79.2\times \frac{5}{18}\text{m/s}$$

$$\text{Speed}=4.4\times 5=22\text{m/s}$$

When a train crosses a stationary pole, the distance covered is equal to the length of the train.

$$\text{Length of the train}=\text{Speed}\times \text{Time}$$

$$\text{Length of the train}=22\text{m/s}\times 7\text{sec}=154\text{m}$$