A man standing on a cliff claps his hand hears its echo after 1 sec . If sound is reflected from another mountain and velocity of sound in air is 340 m / sec . Then the distance between the man and reflection point is

Options

A. 680 m
B. 340 m
C. 85 m
D. 170 m

Answer

To solve the problem, we need to determine the distance between the man and the point where the sound is reflected (the mountain).

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The man claps his hands, and the sound travels to a mountain and reflects back to him.
- The total time taken for the sound to travel to the mountain and back is given as 1 second.

2. **Using the Speed of Sound**:
- The speed of sound in air is given as 340 m/s.

3. **Calculating Total Distance**:
- Since the sound travels to the mountain and back, the total distance traveled by the sound is twice the distance from the man to the mountain.
- Let the distance from the man to the mountain be \( D \).
- Therefore, the total distance traveled by the sound is \( 2D \).

4. **Using the Formula for Distance**:
- The formula for distance is given by:
\[ \text{Distance} = \text{Speed} \times \text{Time} \]
- In this case, the total distance \( 2D \) can be expressed as:
\[ 2D = \text{Speed of sound} \times \text{Total time} \]
- Substituting the values:
\[ 2D = 340 \, \text{m/s} \times 1 \, \text{s} \]
- Therefore:
\[ 2D = 340 \, \text{m} \]

5. **Solving for Distance \( D \)**:
- To find \( D \), we divide both sides of the equation by 2:
\[ D = \frac{340}{2} = 170 \, \text{m} \]

6. **Conclusion**:
- The distance between the man and the reflection point (the mountain) is \( 170 \, \text{meters} \).