For problems 13 - 15 . mo 120 2 F 120 Three steel balls of mass in are positioned in a plane at the ends a three rods of- length L, with fixed angular separation 120 between them. The rods are free is rotate about the central axis perpendicular to their attached ends. The masses of the rods are negligible . At t=0 , a force F is applied perpendicular to each rod. It is applied at the midpoint of two of the rods , and at the end of the third vad , as in the figure above . Friction at the axis of rotation and air resistance are negligible . Let m= 2 kg , L = 2 m , and F = /DON . 313 ) ET(FJ At t= 2s, the force Fis turned off. The angular velocity of the three balls satisfies w= 100 ralls. (Hint : use Newton's "and law for rotations"; what is the rotational inertia for a single mass in a distance ( from the notation axis ) 14) ErIF] Af Ecas, the total rotational KE of the three balls is LooJ . 15 ) CT/F] At += 45 one of the steel balls is pulled towards the rotation aris, along the rod. when the ball reaches the rod's midway point. It's tangential velacity has increased by a factor 4/3 compared to its tangential velocity at t= 35. (Hint : is angular momentum conserved? How are the tangential and angular velocities related? )