1. POSITION A POSITION B Axis of Rotation A rigid assembly consists of three identical uniform bars with an extra mass attached to one of them, as shown. The assembly can spin freely in the vertical plane about the point connecting the bars. Initially, the assembly is at rest in position A. The extra mass is then given a very slight disturbance. Shortly after, the assembly is observed to be in position B. Between positions A and B, the angular momentum of the system is (A) conserved, because the net force is zero (B) conserved, because the net torque is zero (C) conserved, because the rotational inertia is constant (D) not conserved, because of the torque provided by gravity (E) not conserved, because of the torque provided by the force at the pivot pointA skater on ice begins to spin in the camel position, as shown in the figure to the left below. As she continues to spin, she straightens up, pulls her arms to her chest, and crosses her legs to spin in the corkscrew position, as shown in the figure to the right below. Air resistance and friction are negligible as the skater spins. Camel Corkscrew Position Position 2. Which of the following statements about the skater's motion is true? (A) Her angular momentum increases when she moves to the corkscrew position because her angular speed increases. (B) Her angular momentum increases when she moves to the corkscrew position because her rotational inertia increases (C) Her angular momentum remains the same when she moves to the corkscrew position because there is negligible frictional torque. (D) Her angular momentum decreases when she moves to the corkscrew position because her angular speed increases. (E) Her angular momentum decreases when she moves to the corkscrew position because her rotational inertia decreases.3. Which of the following statements about the skater's motion is true? AP Test Booklet Unit 5.4 Angular Momentum 10 Daily (A) Her rotational inertia increases when she moves to the corkscrew position because her angular speed increases. Her rotational inertia increases when she moves to the corkscrew position because her mass is distributed (B) closer to her axis of rotation. Her rotational inertia decreases when she moves to the corkscrew position because her angular speed (C) decreases. (D) Her rotational inertia decreases when she moves to the corkscrew position because her mass is distributed closer to her axis of rotation. Her rotational inertia remains the same when she moves to the corkscrew position because there is negligible (E) frictional torque.The disk on the bottom has a rotational inertia of In and is spinning clockwise on a herimntal surface having negligible friction at an angular speed of 30.1\". The top disk is then dropped directly on top ot'the bottom disk. The top disk has a rotational inertia of In and was initially ginning counterclockwise at an angular speed of mg. IFthe initial total kinetic energy of the two-disk system was 1 what will the kinetic energy ofthe system be once the objects reach a common angular speed? 'I'eil Bottled Unit 5.4 Angular Momentum It} Daily {A} 30310 {B} Ent {c1 Enfci {D} 4Eui'5 {E} En 5. A projectile of mass 0.2 kg and an initial velocity of 50 m/s collides with the end of a blade attached to a turbine. The rotational inertia of the turbine is 12.5 kg - m". Assume the loss of energy of the projectile in the collision is completely transferred to the blades, causing them to spin. If the final rebound velocity of the projectile after hitting a turbine blade is -25 m/s, which of the following is most nearly the rotational velocity of the turbine after the collision? (A) 3.2 rad/s (B) 5.5 rad/s (C) 10.0 rad/s (D) 15.0 rad/s (E) 30.0rad/s 6. A small solid sphere is released from rest at the top of an inclined plane as shown. The sphere rolls down without slipping and reaches the bottom of the plane. How would the angular momentum of the sphere at the bottom of the plane change if the coefficient of static friction between the sphere and the plane were increased?(A) It would decrease because the force of friction would be greater. (B) It would decrease because the net torque would be larger. (C) It would increase because the angular acceleration would increase. (D) It would increase because the linear acceleration would increase. (E) It would remain the same because the net torque would remain the same. 7. V A solid sphere is placed on a frictionless floor in a very long corridor and is given a quick push so that it begins to slide, without rotating, along the corridor. How would the angular speed of the sphere be changing if the floor were not frictionless? (A) It would be increasing until the slipping between the sphere and the floor stops. (B) It would be increasing until the translational motion stops. (C) It would be increasing until the linear and the angular speeds become equal. (D) It would remain zero because the net torque is still zero. (E) It would remain zero because the angular momentum is conserved.8. L O V A clay sphere is traveling horizontally with speed v when it strikes a rod of length L that is suspended from one end and has a rotational inertia of = ML about its pivot point, as shown above. The clay sphere sticks to the rod, which begins to swing about the pivot. If both objects have mass M, the initial angular speed of the sphere-rod system just after the collision is (A) (B) AL (C) (D) I (E)9. m V Side View Top View Two spherical magnetic marbles of equal mass approach each other with equal speeds from opposite directions, with their edges along the same line. When they are side by side, they connect and move as a system. Consider the effects of friction and spin to be negligible. Which statement correctly describes any changes in the angular momentum of an individual marble or of the two-marble system? Individual Marble Two-marble System (A) Decreases Decreases Individual Marble Two-marble System (B) Decreases Remains the same Individual Marble Two-marble System (C) Remains the same Remains the same Individual Marble Two-marble System (D) Increases Remains the same Individual Marble Two-marble System (E) Increases Increases10. At a playground a student runs at a speed of 5 m/s and jump onto a circular disk of radius = m that is free to rotate around a fixed vertical axle. The student jumps on the disk several times, and the angular speed after the student lands is measured each time. Which of the following angular speeds is not a reasonable value for the measured angular speed? (A) 0.5 rad/s (B) 1 rad/s (C) 2 rad/s (D) 3 rad/s (E) 4 rad/s