Which of these shows an oscillatory motion ?

Options

A. Catapult
B. Pendulum
C. Spinner
D. Train

Answer

To determine which of the given options shows oscillatory motion, we need to analyze each option based on the characteristics of oscillatory motion. Oscillatory motion is defined as a to-and-fro movement around a fixed mean position.

### Step-by-Step Solution:

1. **Understand Oscillatory Motion**:
- Oscillatory motion is a repetitive movement back and forth around a central point (mean position).
- It is characterized by a fixed mean position and periodicity.

2. **Evaluate the Catapult**:
- A catapult operates by stretching a rubber band and releasing it to launch an object.
- The motion of the object is not to-and-fro; instead, it follows a projectile path.
- **Conclusion**: A catapult does not show oscillatory motion.

3. **Evaluate the Pendulum**:
- A pendulum swings back and forth around a fixed point.
- When displaced from its mean position, it moves to one side, returns to the mean position, and then moves to the opposite side before returning again.
- **Conclusion**: A pendulum exhibits oscillatory motion.

4. **Evaluate the Spinner**:
- A spinner rotates around a central axis.
- This motion is circular and does not involve moving back and forth around a fixed point.
- **Conclusion**: A spinner does not show oscillatory motion.

5. **Evaluate the Train**:
- A train moves along a track in a straight line.
- It does not move back and forth around a fixed point; rather, it travels in one direction.
- **Conclusion**: A train does not exhibit oscillatory motion.

### Final Conclusion:
Among the options evaluated, only the pendulum shows oscillatory motion.