Question

A train 120 meters long takes 9 seconds to cross a platform 180 meters long. What is the speed of the train in km/h?

• A. 90 km/h
• B. 100 km/h
• C. 120 km/h
• D. 80 km/h

Hint:

To convert speed from m/s to km/h, multiply by \(\frac{18}{5}\).

Answer 1

The Correct Option is C

Step 1: Determine the total distance the train travels to clear the platform. This is the sum of the train's length and the platform's length.
\quad Distance = Train Length + Platform Length = 120 m + 180 m = 300 m
Step 2: The time elapsed for the crossing is 9 seconds.
Step 3: Calculate the train's speed in meters per second (m/s) using the formula: Speed = Distance / Time.
\quad Speed = \( \frac{300}{9} = 33.\overline{3} \, m/s \)
Step 4: Convert the speed from meters per second (m/s) to kilometers per hour (km/h). This is achieved by multiplying by \( \frac{18}{5} \).
\quad Speed = \( 33.\overline{3} \times \frac{18}{5} = 33.\overline{3} \times 3.6 = 120 \) km/h
Step 5: The final calculated speed of the train is 120 km/h.