The clocks and watches which are used for measuring time are based on :

Options

A. rectilinear motion
B. circular motion
C. periodic motion
D. rotational motion

Answer

**Step-by-Step Solution:**

1. **Understanding the Types of Motion**: First, we need to identify the different types of motion mentioned: rectilinear motion, circular motion, periodic motion, and rotational motion. Each type of motion has specific characteristics.

2. **Identifying the Function of Clocks and Watches**: Clocks and watches are instruments designed to measure time. They do this by indicating the passage of time through their moving parts.

3. **Analyzing the Motion of Clocks and Watches**:
- Clocks and watches have hands (hour hand, minute hand, second hand) that move in a specific pattern.
- The movement of these hands is repetitive and occurs at regular intervals.

4. **Defining Periodic Motion**: Periodic motion is defined as motion that repeats itself after a fixed time interval. This is the key characteristic that applies to the motion of the hands of a clock or watch.

5. **Conclusion**: Since the hands of clocks and watches move in a repetitive manner at regular intervals, we can conclude that the motion they exhibit is periodic motion.

6. **Final Answer**: Therefore, the clocks and watches which are used for measuring time are based on periodic motion.

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