This demonstration is more complicated because it involves a vector. For a rotat
ID: 1907041 • Letter: T
Question
This demonstration is more complicated because it involves a vector. For a rotating wheel, the direction of the angular momentum, , is found by curving the fingers of your right hand in the direction of the rotation, your thumb then points along . The angular momentum vector is perpendicular to the plane of the wheel. Sit on the rotating stool used in part II. Hold a bicycle wheel with its axis vertical. While the stool is at rest, have your partner spin the bicycle wheel. Carefully note the direction of spin of the wheel and of the stool. Give an explanation in terms of conservation of angular momentum. While the stool is still rotating, carefully turn the bicycle wheel upside down. Explain what happens.Explanation / Answer
If no net external torque acts on a system, the total angular momentum of the system remains constant. A person holding a spinning bicycle wheel on a rotating chair. The person then turns over the bicycle wheel, causing it to rotate in an opposite direction. Initially, the wheel has an angular momentum in the upward direction. When the person turns over the wheel, the angular momentum of the wheel reverses direction. Because the person-wheel-chair system is an isolated system, total angular momentum must be conserved, and the person begins to rotate in an opposite direction as the wheel. The vector sum of angular momentum and momentum is conserved.