# Angular acceleration and angular velocity

by John78
Tags: acceleration, angular, velocity
 P: 21 1. The problem statement, all variables and given/known data Calculate the angular acceleration and angular velocity of a 4 kg object rotating in a circle of 3 m radius in a time of 6 s. 2. Relevant equations 3. The attempt at a solution Angular acceleration = ω2*r C=2∏r= 2*3.14*3=18.84 360°/57.3°=6.28 rad/s 6.28/6= 2.09 rad/sec Angular acceleration= (2.09)2*3=12.54??????? Angular velocity= angular displacement/time ???? I just want to check whether my working is correct or not.
 P: 297 Nope.Its not right. Remember, angular acceleration is dw/dt. The acceleration w^2*r is centripetal accelwration. Infact writing angular acceleration as w^2*r is dimemsionally inconsistent. As nothing had been told about how w changes with time nothing can be said about angular acceleration. In such cases w is assumed to be constant making angular acceleration 0
 P: 21 angular acceleration = 0 what about angular velocity?
HW Helper
Thanks
P: 26,148
Angular acceleration and angular velocity

Hi John78!
 Quote by John78 angular acceleration = 0
Correct.