1. The problem statement, all variables and given/known data Hi, I'm taking AP Physics in high school, and the explanation I wrote is based on a demo in class, something like this picture: When the wheel is spinning, there is an angular momentum facing away from the string along the axis of rotation of the wheel. The gravitational force creates torque, which points not downward but parallel to the floor and perpendicular to the rod. Torque, a cross product of radius and force, represents the rate of change in angular momentum over time—torque causes change in angular momentum. The rod-wheel system was slowly turning about the string because angular momentum was constantly turning towards the direction of the gravitational torque. The wheel cannot drop towards the floor because the gravitational torque only accounts for horizontal change in angular momentum of the wheel. Is this explanation correct? If there's anyway i can phrase better, please let me know.