A train 135 metres long Is running with a speed of 54 km per hour .In what will it pass a telegraph post ?

Options

A. 9 sec
B. 12 sec
C. 8 sec
D. 6 sec

Answer

To solve the problem of how long it takes for a train to pass a telegraph post, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Length of the Train**:
- The length of the train is given as 135 meters.

2. **Convert the Speed from km/h to m/s**:
- The speed of the train is given as 54 km/h.
- To convert km/h to m/s, we use the conversion factor \( \frac{5}{18} \).
- Calculation:
\[ \text{Speed in m/s} = 54 \times \frac{5}{18} = 54 \times \frac{5}{18} = 15 \text{ m/s} \]

3. **Use the Formula for Time**:
- The time taken to pass the telegraph post can be calculated using the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]
- Here, the distance is the length of the train (135 meters) and the speed is 15 m/s.

4. **Calculate the Time**:
- Substitute the values into the formula:
\[ \text{Time} = \frac{135 \text{ m}}{15 \text{ m/s}} = 9 \text{ seconds} \]

5. **Conclusion**:
- Therefore, the time taken for the train to pass the telegraph post is 9 seconds.

### Final Answer:
The train will pass the telegraph post in **9 seconds**.

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