Attaching 'spinners' to a car causes a rim to spin when stopped at a red light.

When the car picks up speed again, the spinners slow down to a halt.

Why is this?

  • $\begingroup$ More information needed - What is "perpendicular to the red light"? Was it like the wheels on a car stopped facing the light? Or like the wheel on a bike on the back of that car? $\endgroup$ Nov 20 '18 at 20:42
  • $\begingroup$ @maurymarkowitz see edit. $\endgroup$ Nov 20 '18 at 21:44
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    $\begingroup$ Ok, one last question (I promise!), where did you see this effect? In a video? Out the window of a car? $\endgroup$ Nov 20 '18 at 22:05
  • $\begingroup$ Do spinners actually slow down when the car accelerates? Or did you mean that the wheels catch up to the rotational speed of the spinners making them look more like normal wheels with regular rim covers (for the time being when rims and spinners have the same rotational speed) $\endgroup$
    – Alex Doe
    Nov 21 '18 at 1:46
  • $\begingroup$ @AlexDoe if they did, then why do spinners stop rotating while in motion? $\endgroup$ Nov 21 '18 at 19:59

There's a bearing between the "spinner" and the wheel. When the car accelerates away the spinner stays stationary until the small frictional coupling spins it up to the speed of the wheel. When the car stops, angular momentum keeps the spinner turning.

If the spinner is weighted, it doesn't rotate and appears to be stationary all the time.

The patent (Gragg Patent US5290094A) has drawings of the mechanics.

Butler patent US30055906A (1959) shows that this is not a new idea. The spinner may be driven by a drive belt, a drive pulley, and/or a disk brake rotor - have a look at the details in this patent Miansian patent application US20110156473A1

Search for spinners and floaters on youtube to see them in action.

  • $\begingroup$ Found an older patent from Pete US2169237A 1939 patents.google.com/patent/US2169237A/en $\endgroup$
    – D Duck
    Nov 20 '18 at 23:47
  • $\begingroup$ How does this explain them slowing down when the car speeds up? $\endgroup$ Nov 21 '18 at 14:18
  • $\begingroup$ But if the spinner is already spinning (because of angular momentum), why does it come to a halt when the car accelerates? Does it take away all its momentum in the relative frame? $\endgroup$ Nov 21 '18 at 14:19

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