The particles in Figures are connected by a very light rod

The particles in Figures are connected by a very light rod whose moment of inertia can be neglected. They rotate about the y axis with angular velocity ? = 2 rad/s.
(a) Find the speed of each particle, and use it to calculate the kinetic energy of this system directly from ?1/2mivi2.
(b) Find the moment of inertia about the y axis, and calculate the kinetic energy from K = ?1I?2.