What variables are constant in uniform constant motion?

[iwillbeatthis]

I'm confused - getting different answers from different places. During uniform circular motion, I know speed is constant, but what about velocity, acceleration angular acceleration? TBR says velocity is constant in terms of magnitude but not direction, which makes sense. What about the other 2 variables ^^?

Which is correct?

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[Blueprint MCAT Tutor]

Speed: constant
Velocity: changing because of changing direction
Acceleration: constant magnitude (it's a constant centripetal acceleration pointing in towards the center of the circle) but changing direction
Angular Acceleration: constant, and equal to 0

Angular acceleration is the change in the angular velocity. Angular velocity, measured in radians per second, or degrees per second is technically a pseduovector quantity but in MCAT problem solving you should just think of it as a scalar one. Just read "angular velocity" as "angular speed" and you'll be fine for the MCAT. So if something is going, say a constant 45 rpm then its angular speed would be (45*360) / 60 = 270 degrees per second. That's not changing so its angular acceleration is zero.

Hope this helps!

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Bryan, Next Step MCAT Tutor
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[Schenker]

Acceleration: constant, it's a constant centripetal acceleration pointing in towards the center of the circle

Acceleration is changing. As you said, the acceleration vector points radially inwards, which means that its direction changes as the object traverses a circle.

http://en.wikipedia.org/wiki/File:Uniform_circular_motion.svg

Its magnitude is constant.