Are all periodic motions oscillatory ?

Answer

### Step-by-Step Solution:

1. **Understanding Periodic Motion**:
- Periodic motion is defined as a motion that repeats itself at regular intervals of time. Examples include the motion of a pendulum, the rotation of planets, or a car traveling a fixed route daily.

2. **Understanding Oscillatory Motion**:
- Oscillatory motion is a specific type of periodic motion where an object moves back and forth around a central point or equilibrium position. Examples include a swinging pendulum or a mass on a spring.

3. **Identifying Non-Oscillatory Periodic Motion**:
- Not all periodic motions exhibit the back-and-forth movement characteristic of oscillatory motion. For instance, the motion of planets around the Sun is periodic because it repeats in a cycle (the orbit), but it does not involve oscillation around a central point.

4. **Example of Non-Oscillatory Motion**:
- Consider the daily commute from home to office. This motion is periodic because it happens at regular intervals (daily), but it does not involve oscillation. You travel in one direction to the office and then return, which does not represent oscillatory behavior.

5. **Conclusion**:
- From the examples discussed, we conclude that while all oscillatory motions are periodic, not all periodic motions are oscillatory. Therefore, the answer to the question is "No".