Two trains, each of length 500 meters, start off from rest with speeds of 60 km/h and 45 km/h respectively. After how many minutes does the first train cross the second one?
Two trains, each of length 500 meters, start off from rest with speeds of 60 km/h and 45 km/h respectively. After how many minutes does the first train cross the second one?
Explanation
Convert the speeds of the trains from km/h to m/s
1 km/h = 1000 m/3600 s
Speed of the first train = 60 km/h = (60,000 m/3600 s) m/s = 16.67 m/s.
Speed of the second train = 45 km/h = (45,000 m/3600 s) m/s = 12.50 m/s.
Relative speed = Speed of the first train - Speed of the second train = 16.67 m/s - 12.50 m/s = 4.17 m/s.
Distance = Length of the second train = 500 meters.
Using the formula:
Distance = Speed × Time
Time = Distance / Relative speed = 500 meters / 4.17 m/s = 120.05 seconds.
To convert the time from seconds to minutes, we divide by 60:
Time in minutes = 120.05 seconds / 60 = 2 minutes (approximately).
Therefore, the first train will cross the second train after approximately 2 minutes.