Step 1: Understanding the Question:
We are given the length of a train and the time it takes to pass a stationary pole. We need to calculate the speed of the train and express it in kilometres per hour (km/hr).
Step 2: Key Formula or Approach:
The basic formula for speed is:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
When a train passes a pole, the distance covered is equal to the length of the train.
To convert speed from metres per second (m/s) to kilometres per hour (km/hr), we use the conversion factor \(\frac{18}{5}\).
\[ \text{Speed in km/hr} = \text{Speed in m/s} \times \frac{18}{5} \]
Step 3: Detailed Explanation:
First, identify the given values:
Distance covered = Length of the train = 150 metres.
Time taken = 15 seconds.
Now, calculate the speed in m/s:
\[ \text{Speed} = \frac{150 \text{ m}}{15 \text{ s}} = 10 \text{ m/s} \]
Next, convert the speed from m/s to km/hr:
\[ \text{Speed in km/hr} = 10 \times \frac{18}{5} \]
\[ \text{Speed in km/hr} = 2 \times 18 = 36 \text{ km/hr} \]
Step 4: Final Answer:
The speed of the train is 36 km/hr.