ANGULAR MOMENTUM: ANGULAR MOMENTUM By: Paige, Brianna, & Jennae Slide 2: Anything that rotates keeps on rotating until something or someone stops it. A rotating object has “strength of rotation.” Rotating objects have angular momentum, which is defined as the product of rotational inertia, I, and rotational velocity, ω. Angular momentum = rotational inertia ( I) × rotational velocity (ω) Further Understanding…: Further Understanding… The angular momentum is simply equal to the magnitude of its linear momentum, mv , multiplied by the radial distance , r . m – mass v – speed r – radius Angular Momentum = mvr In the case of an object that is small compared with the radial distance to its axis of rotation, such as a tin can swinging from a string or a planet orbiting around the sun, the angular momentum is simply equal to the magnitude of its linear momentum, mv , multiplied by the radial distance, r. In equation form… Application: Application It is easier to balance on a moving bicycle than on one at rest. When our center of gravity is not above a point of support, a slight torque is produced. When the wheels are at rest, we fall over. But when the bicycle is moving, the wheels have angular momentum, and a greater torque is required to change the direction of the angular momentum. The moving bicycle is easier to balance than a stationary bike. Slide 6: A similar concept is the Law of Conservation of Angular Momentum : the law that states that if no unbalanced external torque acts on a rotating system, the angular momentum of that system is constant. For example, Paige sits on a desk chair with her arms and legs extended. Because of her outstretched limbs, her rotational inertia is large. When she pulls her limbs inward while turning, her rotational inertia decreases; in turn her rotational speed increases. Slide 8: In another demonstration of this concept, Jennae performs fouettés- in doing this, she whips her leg around into a passé position; thus decreasing her rotational inertia. Fin: Fin Congratulations! You now understand the concept of Angular Momentum ! Now go and tell all your friends!