1Q40.u1 - Conservation of Angular Momentum Model
This demonstration shows that when the effective radius of a rotating system is reduced, the angular speed increases to conserve angular momentum.
Clamp the base of the apparatus to the corner of a table. Ensure that the string that feeds to the handles is free moving with no erronious knots in the string.
Start the masses spinning. Then, slowly pull up on the handle, pulling the masses in and thus decreasing the moment of inertia of the system. The experiment can also be used to show that the force needed to hold the masses in place increases as they are pulled toward the center. As a result, the masses cannot be pulled all the way in until the system is slowed by friction.