# Why do moving objects stay balanced

1. Mar 27, 2012

### yup790

Why do gyrascopes or things moving in a stright line not fall over. Probably a simple answer but i cannot work it out.

2. Mar 27, 2012

### K^2

Whether a thing moving in a straight line falls over or not depends on a number of factors. Try to send a single ice skate along the surface some time. You'll see that it does fall over quite easily. Rolling things don't fall over because of gyroscopic effect. And gyroscopic effect has to do with torque and angular momentum. If you look up gyroscope on Wikipedia, it will get you started. If you'll have specific questions later on, ask them.

3. Mar 27, 2012

### rcgldr

It would be possible to replace the wheels of a bicycle with large curved ice skate like blades (non-rolling) and because of the steering geometry, the bike would be stable, without any gyroscopic effects.

4. Mar 27, 2012

### K^2

Yes. I never insisted that gyroscopic effect is the only way to achieve stability. Not sure where you got that from. Just wanted to show a clear example of a situation where the object is most certainly unstable, and a lone skate definitely qualifies.

5. Mar 27, 2012

### HallsofIvy

No, that is not true. A bicycle is stable precisely because of the rotation of the wheels, not any "steering geometry".

6. Mar 27, 2012

### chrisbaird

This has been discussed at length on Physics Forums. Search previous threads. Research groups have literally constructed bikes without gyroscopic effects and they still stay upright when in motion, even without a human pilot, because of the steering geometry.