Problems on Trains – Find train speed from pole-crossing time: A 264 m long train passes a pole in 12 seconds. What is the speed of the train in km/h?

Introduction / Context:When a train passes a pole, the distance covered during the crossing equals the train’s own length. With distance and time known, the speed is computed and then converted to km/h.

Given Data / Assumptions:

• Train length = 264 m.
• Time to pass pole = 12 s.
• Pole has negligible length (treated as a point).

Concept / Approach:Speed (m/s) = distance / time. To convert m/s to km/h, multiply by 3.6. Alternatively, compute directly in m/s and then scale.

Step-by-Step Solution:Speed = 264 / 12 = 22 m/s.Speed in km/h = 22 * 3.6 = 79.2 km/h.

Verification / Alternative check:If the speed were 80 km/h, in 12 s the distance would be 80*(1000/3600)*12 ≈ 266.7 m, slightly more than 264 m; hence 79.2 km/h fits exactly.

Why Other Options Are Wrong:80, 80.6, and 82.2 km/h yield distances larger than 264 m in 12 s; 76.8 km/h is smaller than required.

Common Pitfalls:Using the wrong conversion factor (3.6), or dividing time by distance inadvertently.

Final Answer:79.2 km/hr