Which of the following quantities remains constant during uniform circular motion ?

Options

A. Centripetal acceleration
B. Velocity
C. Momentum
D. Speed

Answer

To determine which quantity remains constant during uniform circular motion, we can analyze the characteristics of motion in a circular path.

### Step-by-Step Solution:

1. **Understanding Uniform Circular Motion**:
- In uniform circular motion, an object moves in a circular path with a constant speed. However, it is important to note that while the speed is constant, the direction of the velocity vector changes continuously.

2. **Analyzing Velocity**:
- Velocity is a vector quantity, which means it has both magnitude and direction. In uniform circular motion, although the speed (magnitude of velocity) remains constant, the direction of the velocity vector changes at every point along the circular path. Therefore, the velocity itself is not constant.

3. **Analyzing Speed**:
- Speed is the magnitude of velocity and does not take direction into account. In uniform circular motion, the speed remains constant throughout the motion. For example, if the speed is 2 meters per second, it remains 2 meters per second at all points along the circular path.

4. **Analyzing Linear Momentum**:
- Linear momentum is given by the product of mass and velocity (p = mv). Since the velocity is changing due to the change in direction, the linear momentum will also change. Therefore, linear momentum is not constant in uniform circular motion.

5. **Analyzing Acceleration**:
- In uniform circular motion, there is a centripetal acceleration directed towards the center of the circle. While the magnitude of this centripetal acceleration remains constant (as speed and radius are constant), the direction of the acceleration vector changes continuously as the object moves around the circle. Thus, acceleration is also not constant.

6. **Conclusion**:
- The only quantity that remains constant during uniform circular motion is the speed of the object. Therefore, the answer is that speed remains constant.

### Final Answer:
The quantity that remains constant during uniform circular motion is **speed**.

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