Exploring Rotational Dynamics: The Curious Case of a Spinning Bicycle Wheel

[AARMA]

In a class demonstration, a bicycle wheel was held on an axle and spun. The result came to be that the wheel while rotating held a vertical position while holding it by a string attached to the end of the axle. After the wheel stopped rotating its vertical position ceased and the wheel attained a horizontal position.

How and why does that happen?

 

[rcgldr]

Wiki article:

http://en.wikipedia.org/wiki/Precession

Link to an old series about gyroscopes and some other stuff. Video #9 shows a gyro hanging from a long string.

http://www.gyroscopes.org/1974lecture.asp

 

[AARMA]

can someone explain with his own words.. :)

 

[Cleonis]

In a class demonstration, a bicycle wheel was held on an axle and spun.

On physicsforums:
See this post from november 2010 about https://www.physicsforums.com/showpost.php?p=2992527&postcount=3".


More detailed discussion is in the http://www.cleonis.nl/physics/phys256/gyroscope_physics.php" article on my website.

 

[PJC01]

This phenomenon is an example of rotational dynamics, which is the study of the motion of objects that are rotating around an axis. In this case, the bicycle wheel is rotating around its axle, and the string attached to the end of the axle is providing a centripetal force that keeps the wheel in a vertical position. This is due to the fact that the wheel's angular momentum, which is a measure of its rotational motion, is conserved.

When the wheel is spinning, it has a large amount of angular momentum, which causes it to resist any changes in its orientation. As a result, the wheel maintains its vertical position even when the string is no longer providing a centripetal force. However, once the wheel stops spinning, its angular momentum decreases and it is no longer able to resist the force of gravity, causing it to fall into a horizontal position.

This phenomenon can also be explained by the concepts of torque and moment of inertia. Torque is the rotational equivalent of force, and it is the product of the force applied and the distance from the axis of rotation. In this case, the string is applying a torque on the wheel, keeping it in a vertical position. When the wheel stops spinning, the torque is no longer present and the wheel falls into a horizontal position.

The moment of inertia, on the other hand, is a measure of an object's resistance to changes in its rotational motion. The larger the moment of inertia, the more difficult it is to change the object's orientation. In the case of the bicycle wheel, its moment of inertia is higher when it is in a vertical position, making it more stable and resistant to changes in its orientation.

In conclusion, the curious case of the spinning bicycle wheel can be explained by the principles of rotational dynamics, specifically the conservation of angular momentum, torque, and moment of inertia. This demonstration serves as a great example of the fascinating and complex physics behind the motion of rotating objects.