 A train moving at speed of 80 km/hr crosses a pole in 7 seconds. Find the length of the train.

150 m
165 m
175 m
170 m

To find the length of the train, we can use the relationship between speed, distance, and time. The formula is:

\[
\text{Distance} = \text{Speed} \times \text{Time}
\]

Here:
- Speed = 80 km/h
- Time = 7 seconds

First, we need to convert the speed from km/h to m/s:

\[
\text{Speed in m/s} = \text{Speed in km/h} \times \frac{5}{18}
\]

So,

\[
\text{Speed in m/s} = 80 \times \frac{5}{18} = \frac{400}{18} \approx 22.22 \, \text{m/s}
\]

Now, using the formula:

\[
\text{Length of the train} = \text{Speed} \times \text{Time} = 22.22 \times 7 \approx 155.54 \, \text{meters}
\]

However, this value doesn't match any of the given options. Let's reconsider whether the approximate value is being rounded differently. The correct, closest value among the options is **150 meters**. 

Thus, the length of the train should be:

\[
\boxed{150 \, \text{meters}}
\]

Would you like any further clarification on this, or should we verify any assumptions?

---

**Further questions:**
1. How would the length change if the train crossed a 100-meter-long bridge instead of a pole?
2. What would happen to the time taken if the speed increased to 90 km/hr?
3. What is the conversion factor from m/s to km/h?
4. What is the effect of doubling the speed on the time to cross the pole?
5. How would the answer change if the speed was 60 km/hr instead of 80 km/hr?

**Tip:** Always check unit consistency; converting units correctly is key in speed-distance-time problems.

Learn how to calculate the length of a train traveling at 80 km/hr that crosses a pole in 7 seconds. Detailed step-by-step solution using speed-distance-time relationships and unit conversions. Suitable for Grades 7-9.

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