To find the time taken by the train to cross a bridge, we need to determine the relative speed between the train and the bridge.
Given: Length of the train = 100m Velocity of the train = 60 km/hr
To calculate the relative speed, we convert the velocity of the train to meters per second (m/s):
60 km/hr = (60,000 meters / 3600 seconds) m/s = 16.67 m/s
The relative speed is the sum of the velocities of the train and the bridge since they move in the same direction:
Relative speed = Velocity of train + Velocity of bridge
As the bridge is stationary, its velocity is 0 m/s. Therefore:
Relative speed = 16.67 m/s + 0 m/s = 16.67 m/s
Now we can calculate the time taken by the train to cross the 1 km long bridge:
Distance = Length of train + Length of bridge = 100 m + 1,000 m = 1,100 m
Time = Distance / Relative speed = 1,100 m / 16.67 m/s ≈ 66 seconds
Therefore, it will take approximately 66 seconds for the train to cross the 1 km long bridge.