A train 50 m long passes a platform 100 m long in 10 seconds. What is the train’s speed in metres per second?

Introduction / Context:
Across a platform, total distance equals train length plus platform length. Divide by time to get speed in m/s directly, since distances are in metres and time in seconds.

Given Data / Assumptions:

• L_train = 50 m; L_platform = 100 m.
• t = 10 s.

Concept / Approach:
S = 50 + 100 = 150 m. Speed v(m/s) = S/t = 150/10 = 15 m/s.

Step-by-Step Solution:

Verification / Alternative check:
Converting to km/h: 15 * 3.6 = 54 km/h; plausible for an urban/slow intercity scenario.

Why Other Options Are Wrong:
10 is too low; 50 and 150 are not realistic m/s here; 12 results from 120 m assumption.

Common Pitfalls:
Using only train length for a platform case; unit conversion when not required.

Final Answer:
15