Question

A train 180 m long crosses a pole in 9 seconds. What is the speed of the train?

• A. 20 m/s
• B. 18 m/s
• C. 15 m/s
• D. 25 m/s

Hint:

For train crossing pole problems: \[ \text{Distance travelled} = \text{Length of train} \]

Answer 1

The Correct Option is A

Concept: When a train crosses a pole, the distance travelled by the train is equal to the length of the train itself because the pole is treated as a point object. The formula for speed is: \[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]

Step 1: Identify the given values.
Length of train: \[ 180 \text{ m} \] Time taken: \[ 9 \text{ seconds} \]

Step 2: Understand the actual distance travelled.
Since the train crosses a pole, the train must completely pass the pole. Thus, distance travelled: \[ 180 \text{ m} \]

Step 3: Apply the speed formula.
\[ \text{Speed} = \frac{180}{9} \] \[ = 20 \text{ m/s} \]

Step 4: Write the final answer.
Hence, the speed of the train is: \[ \boxed{20 \text{ m/s}} \]