Circular Motion: Acceleration Direction

[mwahx3]

How would you know the direction of the acceleration of an object
a) moving uniformly in a circular motion
b) accelerating in a circular motion.

I'm pretty sure the answer to a is toward the center of the circle but I'm not so sure about b.

thanks.

 

[Doc Al]

Just by virtue of moving in a circle, the object must have a radial component of acceleration--so your answer for a is correct. If the object is accelerating in a circle, not just moving at constant speed in a circle, then it will also have a tangential component of acceleration. To find the direction of the total acceleration, you need both components.