A say that B is in motion. But C says that B is at rest. Is this possible ?

Explanation

To solve the question, we need to analyze the concepts of motion and rest in the context of different frames of reference.

### Step-by-Step Solution:

1. **Understanding Motion and Rest**:
- Motion is defined relative to a frame of reference. An object is said to be in motion if its position changes with respect to a particular observer or frame of reference.
- Conversely, an object is at rest if its position remains constant with respect to an observer or frame of reference.

2. **Identifying the Observers**:
- In this scenario, we have three entities: A, B, and C.
- A claims that B is in motion, while C claims that B is at rest.

3. **Frames of Reference**:
- For A to say that B is in motion, A must be in a different frame of reference than B.
- For C to say that B is at rest, C must be in the same frame of reference as B.

4. **Possible Situations**:
- If B is moving relative to A (for example, if A is standing still on the ground while B is moving in a vehicle), then A will observe B as being in motion.
- If C is also in the same vehicle as B, then C will observe B as being at rest since they are moving together.

5. **Conclusion**:
- Yes, it is possible for A to say that B is in motion while C says that B is at rest. This is due to the fact that motion and rest are relative concepts that depend on the observer's frame of reference.

### Final Answer:
Yes, it is possible for A to say that B is in motion while C says that B is at rest, depending on their respective frames of reference.

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