Answer:
16.67 m/s.
Step-by-step explanation:
We have been given that a train is 100 m long and it takes 30 seconds to cross a 400 m bridge.
We will use speed formula to solve our given problem.
[tex]\text{Speed}=\frac{\text{Distance}}{\text{Time}}[/tex]
We know that train has to cover the length of bridge and its own length to fully cross the bridge.
[tex]\text{Total distance covered by train}=\text{ Length of bridge+ Length of train}[/tex]
[tex]\text{Total distance covered by train}=400\text{ m}+ 100\text{ m}[/tex]
[tex]\text{Total distance covered by train}=500\text{ m}[/tex]
Time taken by train to cross the bridge = 30 seconds.
Upon substituting these values in speed formula we will get,
[tex]\text{Speed}=\frac{500\text{ m}}{30\text{ seconds}}[/tex]
[tex]\text{Speed}=16.67\frac{\text{ m}}{\text{ second}}[/tex]
Therefore, the trains is going at a speed of 16.67 meters per second.