Some people are able to spin a basketball on the tip of afinger. It is often done by balancing the ball on the tip of thefinger and brushing the other hand along the side of the ball tocause it to rotate. Suppose the ball begins from rest and reaches afinal angular speed of 20.15 rad/s in 1.55 s.

(a) Assuming the ball is subject to a constant angularacceleration, what is the magnitude of the constant angularacceleration? rad/s2

(b) Through how many revolutions does the ball rotate during the1.55 s?