Question

Two trains 100m and 150m long, moving at $30~m/s$ and $20~m/s.$, cross each other. The time taken by the trains to cross each other is:

• A. 5 seconds
• B. 8 seconds
• C. 10 seconds
• D. 12 seconds

Hint:

Relative Speed (opposite) = $S_1 + S_2$; Distance = $L_1 + L_2$.

Answer 1

The Correct Option is A

Step 1: Concept
Total distance to cross = Sum of the lengths of the two trains. Relative speed is used for trains crossing each other.

Step 2: Calculation
Total Distance ($D$) = $100m + 150m = 250m$.
Relative Speed ($S$) = $30m/s + 20m/s = 50m/s$ (Assuming opposite directions for crossing).

Step 3: Formula
Time ($T$) = Distance Speed = $250m / 50m/s = 5s$.

Step 4: Conclusion
The time taken is 5 seconds. Final Answer: (A)