For a particle in uniform circular motion:

• (A) Both velocity and acceleration are constant
• (B) Acceleration and speed are constant but velocity changes
• (C) Both acceleration and velocity changes
• (D) Speed is constant

In uniform circular motion, a particle moves in a circular path at a constant speed. However, its direction changes continuously, which affects its velocity. Let's break down the options:

Understanding the Options

• (A) Both velocity and acceleration are constant: This is incorrect because while speed is constant, the direction of velocity changes.
• (B) Acceleration and speed are constant but velocity changes: This is true. The speed remains the same, but the velocity changes due to the change in direction.
• (C) Both acceleration and velocity change: This is not correct. The speed is constant, so only the direction of velocity changes.
• (D) Speed is constant: This is true, but it doesn't address the changes in velocity.

The Correct Answer

The best choice is (B): Acceleration and speed are constant, but velocity changes. This highlights that while the particle maintains a steady speed, its velocity is always changing due to its circular path.