Comment: Feedback Physics World  August 2017

Fidget physics

Spinning around Using fidget spinners to teach physics concepts such as precession. (Left: CC BY SA Habib M’henni. Right: CC BY SA Superbass)

Even without living with younger children, you can’t but be aware of the toy called a fidget spinner that is now ubiquitous and can be a nuisance when travelling on the bus with school children who continually fiddle with them. However, it seems to me that they could be used as a valuable physics teaching aid. They can be used to demonstrate the conservation of angular momentum, precession of the axis of rotation and stroboscopic effects under fluorescent light. There must be other physics that could be demonstrated with the spinner.

Julian Marks

Wallingford, UK

The current popularity of fidget spinners need not be a distraction: there is a lot of physics in the toy (as also in the kaleidoscope). With some minor modifications to the device, the principles of gyroscopes can be explored, while the gearing of roller-bearings can be discovered (by removing the plastic caps over the bearings and noting the relative angular motions of inner and outer races and the cage itself). Last but not least, spinners can demonstrate aspects of stroboscopy/aliasing, even with only weakly flickering light sources.

Philip Bradfield

Fife, Scotland, UK