For a particle performing uniform circular motion, choose the correct statement (s) from the following.

Options

A. Magnitude of particle velocity (speed) remains constant
B. Particle velocity remains directed perpendicular to radius vector
C. Direction of acceleration keeps changing as particle moves
D. Angular momentum is constant in magnitude but direction keeps changing

Explanation

To solve the question regarding the properties of a particle performing uniform circular motion, we will analyze each statement provided and determine which ones are correct.

### Step-by-Step Solution:

1. **Understanding Uniform Circular Motion (UCM)**:
- In UCM, a particle moves in a circular path with a constant speed. Although the speed (magnitude of velocity) remains constant, the direction of the velocity vector changes continuously.

2. **Analyzing the Statements**:
- **Statement 1**: "Magnitude of particle velocity (speed) remains constant."
- This statement is **true**. In UCM, the speed of the particle does not change; it remains constant throughout the motion.

- **Statement 2**: "Particle velocity remains directed perpendicular to the radius vector."
- This statement is also **true**. The velocity vector at any point in the circular path is tangential to the circle, which is perpendicular to the radius vector drawn from the center of the circle to the particle.

- **Statement 3**: "Direction of acceleration keeps changing as the particle moves."
- This statement is **true**. In UCM, the acceleration (centripetal acceleration) is always directed towards the center of the circle, and as the particle moves, the direction of this acceleration changes continuously while its magnitude remains constant.

- **Statement 4**: "Angular momentum is constant in magnitude but direction keeps changing."
- This statement is **false**. In UCM, the angular momentum of the particle remains constant in both magnitude and direction. The direction of angular momentum is determined by the right-hand rule and does not change as the particle moves in a circular path.

3. **Conclusion**:
- The correct statements regarding the particle performing uniform circular motion are Statements 1, 2, and 3.

### Final Answer:
The correct statements are **1, 2, and 3**.

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