A particle maintaining a constant speed in a circular trajectory experiences both a changing velocity and a changing acceleration. The rationale is as follows:
- Velocity is a vector, possessing both magnitude (speed) and direction. In uniform circular motion, despite constant speed, the direction of motion is perpetually in flux.
- Because velocity is direction-dependent, and circular motion inherently involves a shifting direction, the velocity itself is consequently variable.
- Acceleration quantifies the rate at which velocity changes. In circular motion, acceleration exists even with constant speed due to the continuous alteration of velocity's direction.
- This specific form of acceleration in circular motion is termed centripetal acceleration and is directed inward, toward the circle's center.
- Consequently, even with a stable speed, both the velocity and its rate of change (acceleration) exhibit continuous variation.
Therefore, the accurate conclusion is: Velocity and acceleration are both varying.