4. [MI2 9.E.13] 6/6 points A barbell consists of two small balls, each with mass 450 grams (0.45 kg), at the ends of a very low mass rod of length d = 50 cm (0.5 m). The center of the barbell is mounted on the end of a low mass rigid rod of length b = 0.75 m (see Figure), and this rod rotates counterclockwise with angular speed 130 rad/s. In addition, the barbell rotates clockwise about its own center, with an angular speed 110 rad/s. B b (a) Calculate [. (both magnitude and direction)