Time and Distance – Crossing a bridge at uniform speed: A rider travels over a bridge at 54 km/h and takes 4 minutes to completely cross it. What is the length of the bridge in metres?

Introduction / Context:
Distance equals speed multiplied by time. With speed in km/h and time in minutes, convert to consistent units and then compute metres for the bridge length.

Given Data / Assumptions:

• Speed = 54 km/h.
• Time = 4 minutes.
• Bridge length equals total distance traveled during the crossing interval.

Concept / Approach:
Convert time to hours or speed to m/s. Here we convert time: 4 min = 4/60 h, then compute distance in km and convert to metres.

Step-by-Step Solution:
Time in hours = 4/60 = 1/15 h.Distance in km = 54 * (1/15) = 3.6 km.Distance in metres = 3.6 * 1000 = 3600 m.

Verification / Alternative check:
Converting 54 km/h to 15 m/s, distance = 15 m/s * 240 s = 3600 m.

Why Other Options Are Wrong:
Any value other than 3600 m conflicts with the direct unit-consistent computation.

Common Pitfalls:
Forgetting to convert minutes to hours or misusing 54 km/h as 54 m/s.

Final Answer:
3600 m