Which of the folowing can be zero, when a particle is in motion for some time ?

Options

A. distance
B. displacement
C. speed
D. None of these

Answer

To determine which of the following can be zero when a particle is in motion for some time, we need to analyze the concepts of distance, displacement, and speed.

### Step-by-Step Solution:

1. **Understanding Distance**:
- Distance is defined as the total length of the path traveled by a particle in motion.
- When a particle is in motion, it covers some distance.
- Therefore, distance can never be zero if the particle is in motion.

2. **Understanding Displacement**:
- Displacement is defined as the shortest distance from the initial position to the final position of the particle, which is a straight line.
- If a particle returns to its initial position after moving, the initial and final positions are the same.
- In this case, the displacement is zero because the straight line distance between the initial and final positions is zero.
- Thus, displacement can be zero when a particle is in motion.

3. **Understanding Speed**:
- Speed is defined as the rate of change of position with respect to time.
- Even if a particle moves in a circular path and returns to its starting point, it is still in motion.
- The speed is calculated based on the total distance traveled divided by the time taken.
- Therefore, speed can never be zero if the particle is in motion, as there is a change in position over time.

### Conclusion:
From the analysis:
- **Distance** cannot be zero when a particle is in motion.
- **Displacement** can be zero if the particle returns to its starting position.
- **Speed** cannot be zero when the particle is in motion.

Thus, the correct answer is that **displacement can be zero when a particle is in motion for some time**.