Question

A railway train 80 meters long is travelling at the speed of 54km/h. in what time, will it pass 100 meters long bridge?​

Answer 1

Answer:

It would take 12 seconds for the train to completely pass the bridge.

Step-by-step explanation:

Here, the Train needs to cover the 100 m bridge.

So, we will say Distance = 100 m

But that is incorrect, because, the Question asked is, after how many seconds will it pass the bridge, which means the time taken for the whole train to pass the bridge.

Thus,

Distance = 100 m + length of train

Distance = 100 m + 80 m

∴ Distance = 180 m

Now, the train travels at 54 km/h, but here we are using metres, thus, we must convert it.

So,

54 × (5/18)

= 3 × 5

= 15 m/s

We know that,

Speed = Distance/Time

∴ Time = Distance/Speed

So,

Time taken = 180/15

Time taken = 12s

Thus, it would take 12 seconds for the train to completely pass the bridge.

Hope it helped and you understood it........All the best

Answer 2

Speed and Distance

When a train passes a bridge or platform it has to cover a distance which is equal to sum of its length and bridge’s length.

Length of train $=80\ meters$

Length of bridge $=100 \ meters$

Speed of train $= 54\ km/h$

Speed of train in m/s $=54\times\frac{5}{18}=15\ m/s$.

Total distance $= (80+100)\ m$

Time taken $=\frac{distance}{speed}$  $=\frac{80\ m+100\ m}{15\ m/s}=12s$

So, the time taken by the train to cross the bridge is 12 seconds.