Without stopping the speed of the train is 120 kmph , with stopping the speed of the train is 80 kmph . Find the stop time of the train ?

Options

A. 10 m
B. 15 m
C. 20 m
D. 25 m

Explanation

To solve the problem, we need to find the stop time of the train based on its speeds without stopping and with stopping.

### Step-by-Step Solution:

1. **Identify the Speeds**:
- Speed of the train without stopping = 120 km/h
- Speed of the train with stopping = 80 km/h

2. **Understand the Concept**:
- The difference in speed when the train stops is due to the time it takes to stop. This time is what we are trying to find.

3. **Calculate the Difference in Speed**:
- Difference in speed = Speed without stopping - Speed with stopping
- Difference in speed = 120 km/h - 80 km/h = 40 km/h

4. **Relate the Difference in Speed to Time**:
- The difference in speed (40 km/h) represents the effect of the stopping time on the overall journey.
- If we denote the stop time as \( t \) hours, we can express the distance covered during the stop time as:
\[ \text{Distance} = \text{Speed} \times \text{Time} \]
- The distance covered while the train is stopped can also be expressed as:
\[ \text{Distance} = 80 \times t \]
- Since the train would have covered the same distance without stopping, we can set up the equation:
\[ 120 \times t = 40 \times t \]

5. **Solve for Stop Time**:
- Rearranging gives us:
\[ 120t - 40t = 0 \]
- This simplifies to:
\[ 80t = 0 \]
- Thus, we find that the stop time \( t \) is:
\[ t = \frac{40}{40} = 1 \text{ hour} \]

### Final Answer:
The stop time of the train is **1 hour**.