Question

A train $50\text{m}$ long passes over a bridge at a velocity of $30\text{km/h}$. If it takes $36\text{s}$ to cross the bridge, then the length of the bridge is -

• A. $\text{100 m}$
• B. $\text{200 m}$
• C. $\text{250 m}$
• D. $\text{300 m}$

Answer 1

The correct option is C $\text{250 m}$

Given :

$l=50\text{m}$
$v=30\text{km/h}=30\times \frac{5}{18}=\frac{25}{3}\text{m/s}$
$t=36\text{s}$

The total distance covered by train engine to cross the bridge is,

$d=50+L$

Here, $L$ is the length of the bridge.

So,

$50+L=vt$

$\Rightarrow L=\frac{25}{3}\times 36-50$

$\Rightarrow L=250\text{m}$

Hence, option $\left(C\right)$ is the correct answer.