Why doesn't a spinner want to fall?
It’s much more fun to study the laws of physics with a spinner in your hand!
- Only under adult supervision!
- Be careful when using the drill!
Remove the spinner’s plastic lining. Insert a screw into the hole in the center of the spinner and tighten it. Make a loop in the string. Set the spinner in motion (we used a drill to increase the speed of the spin) and hook the end of the screw on the loop or balance it on a straw. Let it spin, and something incredible will happen! Instead of falling, the spinner will continue to rotate vertically, and will also start to revolve around the fulcrum! You might exclaim: “This is impossible!” – and a physicist would answer, “No, this is just precession.”
Angular momentum characterizes rotational motion the same way that ordinary momentum characterizes translational motion. This angular momentum of a body is determined relative to a selected point of reference, and depends on the body's mass and velocity, as well as on the distance between the body and the reference point. The rotating spinner has a large angular momentum relative to its own axis of rotation. The acceleration of the rotating spinner doesn't coincide with the direction of gravity due to the peculiarities of the law of change of angular momentum. Moreover, the force of gravity changes only the direction of the angular momentum, without changing its value. Under the influence of gravity, the spinner starts spinning around the fulcrum instead of falling over.This additional rotation is called precession. The rotating spinner is a simple form of a gyroscope, a device that allows you to determine the spatial orientation of a support. Gyroscopes are widely used in navigation and stabilization systems. Even our planet Earth is a giant top, the axis of rotation of which is inclined relative to its plane of orbit. The Moon and the Sun create tidal forces which create a rotational moment. Under the influence of these forces, the Earth's axis slowly precesses, returning to any set “starting point” approximately once every 26,000 years.