Question

A $150m$long train is moving with a uniform velocity of $45km/hr$. The time taken by the train to cross a bridge of length $850m$ is

• A. $56sec$
• B. $68sec$
• C. $80sec$
• D. $92sec$

Answer 1

The correct option is C

$80sec$

Step 1. Given data

Length of the train is $L_t=150m$

Speed of train is $v=45km/hr$

Length of the bridge is $L_b=850m$

Step 2. Time taken to cross the bridge

The total distance the train needs to cover to cross the bridge is

$$\begin{gathered} d=L_t+L_b=150+850 \\ =1000m=1km \end{gathered}$$

Time taken to cross the bridge

$$\begin{gathered} t=\frac{dis\tan ce}{speed}=\frac{1}{45}hr \\ =\frac{60\times 60}{45}=80sec \end{gathered}$$

Hence, option C is correct