A train starts from Delhi at 10.30 am and reaches Chandigarh at 12.30 pm . While another train starts from Chandigarh at 10.30 am and reaches Delhi at 12.30 pm . At what time will they start to cross each other if they are running on parallel tracks ?
Answer & explanation
Correct answer: option 3
Train 1 takes 2 hours to reach Chandigarh from Delhi and train 2 takes 2 sec to reach Delhi from Chandigarh .
Ratio of train 1 : train 2
Time 2 hours : 2 hours
Time 1 : 1
Speed 1 : 1
Distance 1 × 1 : 1 × 1
Distance 1 : 1
Distance = Speed × Time
total distance = 2R
As trains moves in opposite direction . so relative speed = (1 + 1 )R = 2R m/sec
Time taken by trains to cross each other = \(\frac{2R}{2R}\) = 1 hour
so trains will cross each other at 11:30 am .