A local train at 29 km/h and an express train at 65 km/h run in the same direction on parallel tracks. From the local’s cab, the faster train takes exactly 16 seconds to pass by. What is the length of the faster train (in metres)?

Introduction / Context:
For same-direction trains, use relative speed (difference). The faster train’s length equals (relative speed) * (overtaking time), since we observe it pass a reference point in the local cab.

Given Data / Assumptions:

• Speeds: 65 km/h and 29 km/h.
• Overtaking time = 16 s.

Concept / Approach:
Relative speed = (65 − 29) km/h = 36 km/h = 10 m/s. Length = 10 * 16 = 160 m.

Step-by-Step Solution:

Verification / Alternative check:
Unit-consistent multiplication yields metres directly.

Why Other Options Are Wrong:
60/120/240 m do not match the observed 16 s at 10 m/s.

Common Pitfalls:
Adding speeds instead of subtracting for same-direction motion.

Final Answer:
160 m