How long will a 130 m long train traveling at 40 km/h take to pass a kilometer stone (a fixed point)?

Introduction / Context:
Passing a fixed point requires the train to cover its own length at its speed. We convert the speed to m/s to work with seconds and meters.

Given Data / Assumptions:

• L = 130 m.
• v = 40 km/h.

Concept / Approach:
40 km/h = 40 * 1000/3600 = 11.111... m/s. Time = distance / speed = L / v.

Step-by-Step Solution:
t = 130 / 11.111... ≈ 11.7 s.

Verification / Alternative check:
At 11.111... m/s for 11.7 s, distance ≈ 130 m, confirming the calculation.

Why Other Options Are Wrong:
11.2, 11, or 12 s are rounded values that do not match the precise quotient 130/11.111....

Common Pitfalls:
Leaving speed in km/h while using seconds, or mis-rounding the m/s conversion.

Final Answer:
11.7 sec