How to Use a Magnetic Gyro Wheel Toy to Show Basic Physics

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The first gyroscope was invented by Jean Bernard Leon Foucault in 1852. Foucault experimented with spinning flywheels. He discovered that they were difficult to tilt or move from their course. This is why, today, gyroscopes are used in everything from spacecraft to hand held gaming systems. The magnetic gyro wheel is also marketed as a rail twirler or, more popularly as the Whee-Lo. This toy combines both the properties of magnets and the properties of gyroscopes.

Put the wheel on the rails and tip it to start the wheel spinning. Tip the rails repeatedly to increase the speed of the wheel.

When the wheel is going, try to turn your wrist. See how easy it is to turn the rails while the wheel is spinning.

Tip the rails quickly to force the wheel to go even faster. Now try to tip your wrist. Is it harder?

Explain that the difference is rotational inertia. When a wheel is spinning, it remains in a single plane and is difficult to tip. Rotational inertia is why it's almost impossible to balance on a two wheeled bicycle when it's still. But when the wheels are turning, the bike stays upright easily.

Use gravity to get the gyro wheel started. Tilt the rails to increase the speed. Why does the wheel stay on the track?

Hold the rails still and wait for the wheel to slow down. Watch where it finally flies off the track.

Repeat the experiment and record where the wheel flies off each time.

The wheel stays on the track because of the magnets on the axis of the wheel. They are strong enough to hold the wheel to the track when its moving. But when gravity and friction slow the wheel down enough to allow centripetal force to overpower the magnetic force, it will fly off the rails on the outside curve farthest from the handle.

Ask if using this toy in zero gravity would change the results. The answer is: no it wouldn't. The wheel would still move along the rails because magnets work in zero gravity. Without gravity the wheel would spin longer. But ultimately, friction would slow the wheel. Centripetal force exists in zero gravity as well. So the wheel would still fly off at the same spot on the rails.