I recently visited a children’s science museum and saw an exhibit consisting of a horizontal rotating disk. Visitors could place metal wheels on the surface of the disk and let them roll freely.
I noticed two surprising behaviors. First, once a wheel was rolling on the rotating disk, it did not slide outward or get thrown off the disk, but instead remained stably on the surface. Second, in at least one case, the wheel appeared to advance across the disk rather than losing speed or drifting outward due to friction.
Here is a short video demonstrating the behavior:

https://imgur.com/gallery/spinning-wheels-on-spinning-disk-aL7ij3V

My questions are:
1.)Why does the wheel remain on the rotating disk instead of immediately sliding outward due to centripetal acceleration?

B.)How can the wheel advance across the disk (apparently gaining position) rather than slowing down or being carried outward by frictional forces?

I’m especially interested in the roles of friction, rolling motion, and reference frames in explaining this behavior

Question

I recently visited a children’s science museum and saw an exhibit consisting of a horizontal rotating disk. Visitors could place metal wheels on the surface of the disk and let them roll freely.
I noticed two surprising behaviors. First, once a wheel was rolling on the rotating disk, it did not slide outward or get thrown off the disk, but instead remained stably on the surface. Second, in at least one case, the wheel appeared to advance across the disk rather than losing speed or drifting outward due to friction.
Here is a short video demonstrating the behavior:

https://imgur.com/gallery/spinning-wheels-on-spinning-disk-aL7ij3V

My questions are:
1.)Why does the wheel remain on the rotating disk instead of immediately sliding outward due to centripetal acceleration?

B.)How can the wheel advance across the disk (apparently gaining position) rather than slowing down or being carried outward by frictional forces?

I’m especially interested in the roles of friction, rolling motion, and reference frames in explaining this behavior

Simplifier · Accepted Answer

Okay, let's break down why those wheels do those crazy things!

First, why the wheel stays on the spinning disk instead of flying off. Imagine you're in a car turning a corner. You feel like you're being pushed to the side, right? That's kind of like what the wheel "feels" on the disk. But here's the thing: friction is like a sticky force between the wheel and the disk. This sticky force is strong enough to keep the wheel from sliding outward. It's like the car seat holding you in place as you t

Elementary School Math Teacher · Answer

Okay, that sounds like a super cool exhibit! Let's break down what's happening with those wheels.

A.) The wheel stays on the disk because of a force called "friction." Now, you might think friction always slows things down, but it also helps things grip! As the disk spins, friction between the disk and the wheel's edge actually *pulls* the wheel inward, toward the center. This inward pull balances out the outward push you mentioned, called "centrifugal force" (some people call it centripetal ac

Hobby Electronics Enthusiast · Answer

Hey, that's a cool project idea! I can see why you're curious about the physics at play here.

A.) The wheel stays on the disk because of a balance between forces. Yes, there's a centrifugal force (in the rotating frame of reference) pushing it outward. But there's also friction between the wheel and the disk. This friction acts *inward*, opposing the outward motion. The key is that the inward frictional force is strong enough to counteract the centrifugal force, keeping the wheel from sliding o

Acoustics Engineer · Answer

The behavior you observed with the wheels on the rotating disk is a consequence of the interplay between inertial forces, friction, and the geometry of rolling motion.

First, the wheel remains on the disk due to a balance of forces in the rotating reference frame. While there is an apparent outward centrifugal force, the rolling motion of the wheel introduces a Coriolis force. This force acts perpendicular to the wheel's velocity and the axis of rotation, effectively counteracting the centrifug

Fluid Dynamics Expert · Answer

The behavior you observed arises from a complex interplay of forces in a non-inertial reference frame. First, consider the wheel's stability. While a stationary object on the rotating disk would indeed experience an outward pseudo-force (often called centrifugal force) in the rotating frame, the rolling wheel introduces additional factors. The wheel's rotation generates a gyroscopic effect, resisting changes in its orientation. More importantly, the friction between the wheel and the disk acts n

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