1. Rotational Dynamics 8.3

3. Newton’s Second Law of Rotation Net positive torque, counterclockwise acceleration. Net negative torque, clockwise acceleration.

4. When net torque is zero: Object rotates at constant velocity, Or if object at rest, object does not rotate.

6. Momentum Objects also resist change in their rotational motion. Rotating objects have inertia, and have a momentum assoc. with rotation. Unit: kgm 2 /s

8. Angular momentum is conserved When no net torque is acting on an object or objects, angular momentum is conserved – law of conservation of angular momentum. AB L A = L B I  = I  Animation: http://my.hrw.com/sh/hf2/0030724864/student/ch08/sec03/qc04/hf208_03_q04fs.htm http://my.hrw.com/sh/hf2/0030724864/student/ch08/sec03/qc04/hf208_03_q04fs.htm

9. Kinetic Energy Rotating objects have KE associated with their angular speed. Unit: J Animation: http://my.hrw.com/sh/hf2/0030724864/student/ch08/sec03/qc05/hf208_03_q05fs.htm http://my.hrw.com/sh/hf2/0030724864/student/ch08/sec03/qc05/hf208_03_q05fs.htm

11. Mechanical Energy is Conserved

12. Answer to Sample Problem 8C: 13 Nm Answers to Problem #2 for Practice 8C: 2.) –8.1 Nm

13. Answer to Sample Problem 8D: 0.24 rad/s Answers to Even Problems for Practice 8D: 2.) 24 rad/s 4.) 9.1 x 10 2 m/s

14. Answer to Sample Problem 8E: 5.29 m/s Answer to Problem #2 from Practice 8E: 2.) 12.0 m/s