Question

A train 150 m long is running at a speed of 54 km/hr. How much time will it take to cross a pole?

• A. \(8\) seconds
• B. \(10\) seconds
• C. \(12\) seconds
• D. \(15\) seconds

Hint:

To convert km/hr to m/s quickly, multiply the speed by \( \frac{5}{18} \). For a train crossing a pole, distance travelled equals the length of the train.

Answer 1

The Correct Option is B

Concept: When a train crosses a pole, the distance covered by the train is equal to the length of the train. Time is calculated using the formula: \[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \] Also, speeds must be in m/s when distance is in meters.
Step 1:Convert the speed from km/hr to m/s.
\[ 54 \times \frac{5}{18} = 15 \text{ m/s} \]
Step 2:Use the time formula.
Distance covered = length of train = \(150\) m \[ \text{Time} = \frac{150}{15} = 10 \text{ seconds} \] Thus, the train will take 10 seconds to cross the pole.