A hoop with a mass of 1.2 kg is rotating about a fixed axis through its center and perpendicular to the plane. It has an angular acceleration of 2.0 rad/s2. A point on the rim has a tangential acceleration of 0.80 m/s2. (a) Find the radius of the hoop. (b) At a certain instant, a point on the rim has a tangential velocity of magnitude 3.4 m/s. What is the magnitude of the tangential velocity 2.0 s later? (c) If all the mass is in the rim of the hoop, find the hoop's Irot.