I need help with a problem of mechanics, I want to find the angular acceleration but I only have the angular velocity and the radius, the reason why I need it is because in the problem they're asking me for the acceleration.

Question

anonymous · Answer

Will you give me exact language of question? i'm ready to do help

anonymous · Answer

differentiate your angular velocity with respect to time. That will give you your angular acceleration.

anonymous · Answer

$$a = \omega ^{2}r$$

anonymous · Answer

a= acceleration (in uniform circular motion)
w(omega) = angular velocity
r=radius (of the circle)

anonymous · Answer

no thats linear acceleration you gave there @kausarsalley

anonymous · Answer

@zaphodplaysitsafe    what i gave her is the acceleration in uniform circular motion.....

anonymous · Answer

yes, but whats required is angular acceleration

anonymous · Answer

ok.......so with the question providing her with values how is she going to differentiate that? and since the question gave her a radius (of a circle) then the motion should be a circular motion

anonymous · Answer

yes, precisely that.  and if its uniform circular motion, kindly note that the angular acceleration will be 0.

anonymous · Answer

you meant that in a uniform circular motion, the acceleration is constant not zero....

anonymous · Answer

Hi @kausarsalley, 
i meant angular acceleration is 0 in uniform circular motion. in unifrom circular motion, only the direction of velocity changes, its magnitude is constant. i.e the speed is constant. hence the angular velocity is constant. 
hence, the angular acceleration is 0.

anonymous · Answer

okay, i understand that............so are you saying the answer to the question is zero??

anonymous · Answer

we don't yet. thats why we need to find out what the velocity is. is it time varying or not(in magnitude). if its not, this is uniform circular motion as you said, and the angular acceleration would be 0.

anonymous · Answer

Marfa says she knows the angular velocity. then she must know whether its time varying or not.

anonymous · Answer

oh okay.....then i think that should be it.......

anonymous · Answer

I needed that for yesterday :S but other guy have already helped me :) anyway thnx, my dilema was that I didn't consider that w is constant so the angular velocity is 0 :)

anonymous · Answer

I'll give the medal to zaphodplayitsafe because he mention what I needed thnx guys