A discus thrower changes the angular velocity of his arm from 280/s to 400/s (at the instant of release)in 1.5 s. The discus is located 0.8 m from the axis of rotation. Calculate: a. Tangential acceleration at the midpoint of the time interval. b. Radial (centripetal) acceleration at the midpoint of the time interval c. Tangential velocity at release.