Answer
Speed, instantaneous velocity and radial acceleration are constant in uniform circular motion.
Tangential acceleration is in uniform circular motion.
Work Step by Step
Speed is scalar hence remains constant during uniform circular motion.
At any instant velocity has fixed value and direction so constant.
Tangential velocity changes its direction though not its magnitude.
Radial acceleration is always fixed and towards center thus constant.
Since motion is uniform circular motion so its tangential acceleration is zero.