Question

A 100-meter long train crosses a 200-meter long and 20-meter wide bridge in 20 seconds. What is the speed of the train in Km/hour?

• A. 45
• B. 36
• C. 54
• D. 57.6

Answer 1

The Correct Option is C

To determine the speed of the train in km/hour, we need to calculate the total distance covered by the train and the time taken to cover that distance, and then use the speed formula:

\text{Speed} = \frac{\text{Distance}}{\text{Time}} 

1. Total Distance: The train needs to cross the entire length of the bridge and its own length. The length of the train is 100 meters, and the length of the bridge is 200 meters. Therefore, the total distance covered is:

100 + 200 = 300 \text{ meters}

1. Time: The time taken by the train to cross the bridge is given as 20 seconds.
2. Convert Speed into Km/hour:
   • First, calculate the speed in meters per second using the formula:

\text{Speed in m/s} = \frac{\text{Total Distance}}{\text{Time}} = \frac{300 \text{ meters}}{20 \text{ seconds}} = 15 \text{ m/s}

• To convert m/s to km/h, use the conversion factor 1 m/s = 3.6 km/h:

\text{Speed in km/h} = 15 \times 3.6 = 54 \text{ km/h}

Thus, the speed of the train is 54 km/hour, which matches option 54.