.
Centripetal acceleration  a = 
 = 
 = 2.666... m/s^2.
Angular velocity = 
 radians per second,  where "n" is the number of rotations per second,
which is  n = 
.
In the last formula, the "2" in the numerator is the given speed, and the denominator is the circumference of the circle.
So,  n = 
 = 0.2123 rotations per second,  and therefore angular velocity of the particle is
    
 = 2*3.14*0.2123 = 1.333 radians per second.
Solved.