1 Answers
Option 2 : 2:00 PM
Given:
Length of 1st train = 100 meter
Length of 2nd train = 200 meter
Speed of 1st train = 18 km/h
Speed of 2nd train = 36 km/h
Concept used:
1.) Relative speed is defined as the speed of a moving object with respect to another.
2.) When two objects are moving in the same direction, relative speed is calculated as their difference.
3.) m/s = (km/h) × (5/18)
Formula used:
Speed = Distance/time
Distance = Speed × time
Relative speed when moving in same direction = a – b
Calculations:
Train 1st reaches at point C on 12 AM
Time taken by 1st train to reach at C = 12 AM – 10 AM = 2 hours
Distance between A to C = 18 × 2 = 36 km = 36000 meter
Total distance which is covered by 2nd train to cross the train = 200 + 36000 + 100 = 36300 m
Relative speed of both the trains = a – b = 36 – 18 = 18 km/h = 18 × (5\18) = 5 m/s
Total time taken by 2nd train to cross the 1st train = Distance/speed = 36300/5 = 7260 second
Time taken in hours = 7260/3600 = 2.01 hours ≈ 2 hours
∴ Time to meet of both the friends = 12 AM + 2 hours = 2:00 PM