# Function of gyroscopes

1. Apr 24, 2005

### Werg22

I know the function of gyroscopes and the way a disc always spin perpendicularly to a moving axis. My question is, when a gyroscope is not spinning perpendicularly to the ground, how does it still keep on spinning indefinitely since friction now affects the mechanism?

2. Apr 24, 2005

### brewnog

It doesn't.

If this gyroscope is not powered (as with toy gyroscopes), friction will play its part in slowing down the disc. If the gyroscope is powered (as with most gyroscopes with a practical purpose) then the motor provides the force needed to overcome the friction in the bearings.

3. Apr 24, 2005

### Werg22

But if it is perpendicular to the ground it theorically never stops right?

4. Apr 24, 2005

### brewnog

Theoretically, if no force opposes the motion, then it will keep going. However, you'll always have some friction in the bearings and some air resistance slowing things down.

5. Apr 24, 2005

### Werg22

Yeah, but the centripetal force also causes friction between the disc and and the bar so it won't spin indefinitely, no?

6. Apr 24, 2005

### brewnog

I don't know what you're asking.

It doesn't keep on going forever, because of friction. It will not spin indefinitely.

7. Apr 24, 2005

### Werg22

I mean ignoring air friction, there is friction between the disc and the bar caused by the centripetal force...

8. Apr 24, 2005

### brewnog

Yes! There is!

9. Apr 24, 2005

### pervect

Staff Emeritus
Not really. When you take friction into account, the gyroscope eventually stops. The orientation of the gyroscope really doesn't matter (I'm not sure why you think it's important).

10. Apr 24, 2005

### Werg22

Because gravity will have a component in the spinning direction.

11. Apr 25, 2005

### T@P

no mechanical toy that i know of will go forever. friction is like the grinch or whatever. same in your gyroscope.

does anyone know how they work...?