The physical quantity that changes continuously during uniform circular motion is velocity.

Here's why:

* Uniform Circular Motion: This means an object is moving in a circle at a constant speed.

* Velocity: Velocity is a vector quantity, meaning it has both magnitude (speed) and direction.

* Direction Change: Even though the speed is constant, the direction of motion is constantly changing as the object moves in a circle.

Therefore, the velocity vector is always changing, even though the speed remains the same.