12, 13 and 20. A man in a gym is holding a 8 kg weight at arms length, a distance of 0.55 m from his shoulder joint. What is the torque about his shoulder joint due to the weight of his arm is held at 30 degrees below the horizontal ?

D. 12. A figure skater of moment of inertia 40 kg.m' is initially spinning at a speed of 6 rad/s. If she moves her arms outward, her new moment of inertia is 60 kg.m. What is her new angular velocity? A. 2 rad/s B. 4 rad/s C. 6 rad/s D. 9 rad/s E. 12 rad/s 13. A figure skater spins with an angular velocity of wo on the ice holding his arms out perpendicular to his body. He then brings his arms in towards his body causing his rotational inertia to decrease by a factor of 3. What his new angular velocity? A. Wo 3 B. wo 9 C. Wo D. 3wo E. 9wo