Train Problem (Question)
Concept: Two Trains Crossing Each Other : āϧāĻžā§°āĻŖāĻž: āĻĻā§āĻāĻž ā§°ā§āϞ āĻĒā§°āϏā§āĻĒā§° āĻ āϤāĻŋāĻā§ā§°āĻŽ āĻā§°āĻž
When two trains cross each other, the total distance covered is the sum of their lengths. āϝā§āϤāĻŋā§āĻž āĻĻā§āĻāĻž ā§°ā§āϞ⧠āĻĒā§°āϏā§āĻĒā§° āĻ āϤāĻŋāĻā§ā§°āĻŽ āĻā§°ā§, āϤā§āϤāĻŋā§āĻž āĻŽā§āĻ āĻĻā§ā§°āϤā§āĻŦ āĻš’āϞ āĻĻā§ā§ā§ ā§°ā§āϞ⧰ āĻĻā§ā§°ā§āĻā§āϝ⧰ āϝā§āĻāĻĢāϞāĨ¤
Total distance = Lâ + Lâ : āĻŽā§āĻ āĻĻā§ā§°āϤā§āĻŦ = Lâ + Lâ
Relative Speed (Opposite Direction) : āĻāĻĒā§āĻā§āώāĻŋāĻ āĻāϤāĻŋ (āĻŦāĻŋāĻĒā§°ā§āϤ āĻĻāĻŋāĻļāϤ)
If two trains move in opposite directions, their relative speed is the sum of their speeds. āϝāĻĻāĻŋ āĻĻā§āĻāĻž ā§°ā§āϞ āĻŦāĻŋāĻĒā§°ā§āϤ āĻĻāĻŋāĻļāϤ āĻāϞā§, āϤā§āύā§āϤ⧠āĻāĻĒā§āĻā§āώāĻŋāĻ āĻāϤāĻŋ āĻš’āϞ āĻĻā§ā§ā§ āĻāϤāĻŋā§° āϝā§āĻāĻĢāϞāĨ¤
Relative Speed = Sâ + Sâ : āĻāĻĒā§āĻā§āώāĻŋāĻ āĻāϤāĻŋ = Sâ + Sâ
Time Formula: āϏāĻŽā§ā§° āϏā§āϤā§ā§°
Time = L1 + L2 / S1 + S2 āϏāĻŽā§ = L1 + L2 / S1 + S2
Given Data : āĻĒā§ā§°āĻĻāϤā§āϤ āϤāĻĨā§āϝ
Speed of Train 1 (Sâ) = 110 m/s : Train 1 ā§° āĻāϤāĻŋ = 110 āĻŽāĻŋ/āĻā§
Speed of Train 2 (Sâ) = 140 m/s : Train 2 ā§° āĻāϤāĻŋ = 140 āĻŽāĻŋ/āĻā§
S1 + S2 = 110 + 140 = 250 m/s
Case 1: Numerical Problem : āĻāĻŖāĻŋāϤā§ā§ āĻāĻĻāĻžāĻšā§°āĻŖ
Length of Train 1 (Lâ) = 400 m : Train 1 ā§° āĻĻā§ā§°ā§āĻā§āϝ = 400 āĻŽāĻŋ
Length of Train 2 (Lâ) = 600 m : Train 2 ā§° āĻĻā§ā§°ā§āĻā§āϝ = 600 āĻŽāĻŋ
Soln : āϏāĻŽāĻžāϧāĻžāύ
L1 + L2 = 400 + 600 = 1000 m L
Time = 1000 / 250 = 4 seconds
Final Answer : āĻā§ā§āĻžāύā§āϤ āĻāϤā§āϤ⧰ : Time taken by the two trains to cross each other = 4 seconds : āĻĻā§āĻāĻž ā§°ā§āϞ⧠āĻĒā§°āϏā§āĻĒā§° āĻ āϤāĻŋāĻā§ā§°āĻŽ āĻā§°āĻŋāĻŦāϞ⧠āϞā§ā§ąāĻž āϏāĻŽā§ = ā§Ē āĻā§āĻā§āĻŖā§āĻĄ
Key Exam Tips (SSC / HSLC) : āĻĒā§°ā§āĻā§āώāĻžā§° āĻā§ā§°ā§āϤā§āĻŦāĻĒā§āϰā§āĻŖ āĻāĻŋāĻĒāĻ
- Crossing each other → Add lengths : āĻ āϤāĻŋāĻā§ā§°āĻŽ āĻā§°āĻž → āĻĻā§ā§°ā§āĻā§āϝ āϝā§āĻ
- Opposite direction → Add speeds : āĻŦāĻŋāĻĒā§°ā§āϤ āĻĻāĻŋāĻļ → āĻāϤāĻŋ āϝā§āĻ
- Same direction → Subtract speeds : āĻāĻā§āĻāĻž āĻĻāĻŋāĻļ → āĻāϤāĻŋ āĻŦāĻŋā§ā§āĻ
- km/h to m/s conversion → × 5/18 : km/h ā§° āĻĒā§°āĻž m/s āϞ⧠→ × 5/18