Convert speed to m/s

Convert 72 km/h to meters per second using factor 5/18, so $v = 72 \times \frac{5}{18} = 20\,\text{m/s}$.

$v = 72 \times \frac{5}{18} = 20$

Apply distance formula

When a train passes a pole, the distance covered equals its length, so $L = v \times t$.

$L = v \times t$

Substitute values

Insert $v = 20\,\text{m/s}$ and $t = 10\,\text{s}$ to get $L = 20 \times 10 = 200\,\text{m}$.

$L = 20 \times 10 = 200$

Verify with options

The calculated length matches option B (200 meters).

$L = 200\ \text{m}$