A $246\text{metre}$ long train crosses a pillar in $30\text{seconds}$. Find the speed of the train in $\text{km/h}$.

Given:
Length of the train (Distance) = $246\text{m}$
Time taken to cross a pillar = $30\text{seconds}$

Formula for speed in $\text{m/s}$:

$$\text{Speed}=\frac{\text{Distance}}{\text{Time}}=\frac{246}{30}=8.2\text{m/s}$$

To convert the speed from $\text{m/s}$ to $\text{km/h}$, multiply by $\frac{18}{5}$:

$$\text{Speed in km/h}=8.2\times \frac{18}{5}=\frac{147.6}{5}=29.52\text{km/h}$$

Therefore, the speed of the train is $29.52\text{km/h}$.