Correct Option (4)
To calculate the time required for a train to cross a stationary object, such as a man, the distance covered by the train is equal to its own length. The given parameters are:
- Length of the train (Distance) = 200 meters
- Speed of the train = 40 kmph
For consistent units, the speed must be converted from kilometers per hour (kmph) to meters per second (m/s):
Speed = 40 kmph × (5/18) m/s = (200/18) m/s = (100/9) m/s
Now, apply the formula for time:
Time = Distance / Speed
Time = 200 meters / ((100/9) m/s)
Time = 200 × (9/100) seconds
Time = 2 × 9 seconds
Time = 18 seconds
Thus, the train will cross the man in 18 seconds.
Incorrect Options:
Options (1) 12, (2) 15, and (3) 16 are incorrect. These values do not result from the accurate application of the distance, speed, and time relationship, considering the given train length and speed, and after performing the necessary unit conversions.
