Mi-1 Rotating Stool


To demonstrate the conservation of angular momentum.


  • Rotating stool
  • Dumbbell weight
  • Bicycle wheel

Rotating Stool Rotating Stool Diagram

Rotating Stool and Diagram.


A volunteer student is seated upon the stool holding a dumbbell weight in each hand close to the body. The stool is rotated slowly. The student then outstretches his/her arms and the redistribution of mass requires a change in rotational speed to conserve angular momentum. If initially the student has his/her hands outstretched when the weights are brought in toward the body the increase in rotational speed can be large enough to make it almost impossible to stay seated.