Question

A 60 m long train moving on a straight level track passes a pole in 5 s, the time it will take to cross a 540 m long bridge is

• A. 30 s
• B. 50 s
• C. 20 s

Answer 1

The correct option is B 50 s

Given, length of the train = $60m$, time taken to cross the pole = $5s$ and length of the bridge = $540m$
Speed of the train $=\frac{\text{Length of the train}}{\text{Time taken to cross the pole}}=\frac{60}{5}=12m{s}^{-1}$

Now, distance to be covered to cross a $540m$ long bridge
= Length of the train + Length of the bridge
= $60+540=600m$

Hence, time taken $=\frac{\text{Distance}}{\text{Speed}}$
= $\frac{600}{12}$ = 50 s