When I show the Honda Cog ad (flavors of equilibrium, energy transformations), there is always strong skepticism regarding the wheels that roll uphill. So I am always ready to go with the demonstration illustrated in this previous post.
Sometimes I leave the wheel resting comfortably on the inclined plane. That very same inclined plane is also home to my electronic balance.
So why not another Physics Mashup?
First, students should be able to explain why the wheel holds fast on the incline before I spill the beans. Or in this case, ball bearings.
Next, I tare the scale and rest the "hill-hugger" atop the scale. A reading is observed.
Finally, students should correctly predict what will happen to the scale reading when the incline is re-leveled. Assure them the wheel will remain atop the scale.
It's not so novel it will shatter the Earth. But it's nice to milk some mileage out apparatus just otherwise lying around.
The answer can be seen via the comments. I leave the solution to the reader.