Duplicate tunnel setup – compute tunnel length A 700 m train runs at 72 km/h and crosses a tunnel in 1 minute. What is the tunnel length?

Introduction / Context:
This is the same structure as a prior item: total distance in the interval equals train length plus tunnel length. Convert speed and multiply by time to get distance.

Given Data / Assumptions:

• Train length = 700 m.
• Speed = 72 km/h = 20 m/s.
• Time = 60 s.

Concept / Approach:
Compute D and subtract train length to find tunnel length.

Step-by-Step Solution:

Verification / Alternative check:
Adding back: 700 + 500 = 1200 m in 60 s at 20 m/s — consistent.

Why Other Options Are Wrong:
550 m and 600 m lead to too much distance; 700 m confuses tunnel length with total. Only 500 m works.

Common Pitfalls:
Using only tunnel length in D = v*t. Always include the train length for clearing a tunnel.

Final Answer:
500 m