A 120 m long train crosses a pole in 10 seconds. What is its speed in km/h?

Introduction / Context:
Crossing a pole uses the train’s own length as the distance. Convert the resulting m/s speed to km/h for the final answer.

Given Data / Assumptions:

• L = 120 m.
• t = 10 s.

Concept / Approach:
v_mps = L/t = 120/10 = 12 m/s; v_kmph = v_mps * 3.6.

Step-by-Step Solution:

Verification / Alternative check:
Reverse: 43.2 km/h = 12 m/s; in 10 s it covers 120 m—exact train length.

Why Other Options Are Wrong:
36 or 40 km/h underestimates; 45 km/h overestimates; “None of these” is false because 43.2 km/h matches.

Common Pitfalls:
Using 18/5 incorrectly; rounding 43.2 to 45.

Final Answer:
43.2 km/h