Axes of rotation

[NetSquirrel]

About how many axes (not the chopping kind) can you rotate an object in a gravity- and air-free space, simultaneously? I'm finding this difficult to visualise. Obviously you can take the object and give it a bit of spin about an axis. From then on, can you apply a force that will make it keep spinning, but also spin about a second plane (i.e. make the original axis rotate)? I don't know whether this would just be prevented by the gyroscope effect or not. From then on, can you add more axes of rotation...what's the limit? <BR><BR> I've tried to draw out what I mean (see link) but it looks strange due to Paint Shop Pro not having 3D drawing tools. <BR><BR> http://images.dpchallenge.com/images_portfolio/16982/med ium/113918.jpg

[Hammer]

I think it's 3. Look at one of those zero-gravity simulator thingies on 3 axes here to try and picture it in your mind. It certainly seems to work for me.

[DrWu]

We may not have the conclusive answer but you have to admit it's a better use of this site than "who sang pink?" or what advert was "very very tasty" from!!

[Drewhound]

Thanks for the video NetSquirrel You can do a similar thing yourself by sitting in a chair that will revolve holding a bike wheel by the axle (one hand each side). Get someone to spin the wheel and if you try to turn the axle you go round in circles. Great fun!

    I think it all depends on what you mean by rotate. Eg does the moon rotate about the earth or orbit it? I'd say an object can only spin about an axis within itself, otherwise I'd call it turning. Back to what jenky said in his third post. I'm open to any other offers though :-)

[dholsonbake]

The answer is finite. I can see 6 axes of movment. Axis 1-3 were shown by the original jpg file. If the point has two or more axes of spin this creates a torque as in the moment example of earler postings. Axis 4 & 5 are then the linear and rotational momentum of the first three. Then there is time, so if this ball wabbles rotates and moves in a stright line over a long peiored of time then that would be 6 axis of rotation or movment about a point.

[mccloud]

as for visualizing the theory... (if you've got a program like mathematica you can go and visualize after some easy math. i don't, but the math i can try to explain). there is some formula describing a point on a sphere with sphere-coordinates (kugelkoordinaten, sorry, not native english, me) , using the radius and two angles. (look it up, thx). for a start, if two axes rotate at the same speed, a point on the sphere will describe a figure of eight placed on less than half of said sphere (as opposed to a circle of only one axis rotates. things get more interesting when one varies the spin-speeds (angle per time unit) THIS IS NOT TO SAY THAT IT GETS LESS COMPLICATED. BUT MORE INTERESTING. this is just a small theoretical contribution that may in time help understand the theory and its practical applications, something i certainly don't claim to do. for things do spin around two axes, the third usually being the plane of reference in 3d space and thus immobile. at least in theory.

[basilworks]

Lets consider only two axis of rotation, perpendicular to each other. One along the poles and the other along the equator.

Angular velocity(vector) for the first motion is parallel to the line joining the poles and for the other motion it is perpendicular to the line joining the poles. So the resultant will be the addition of these angular velocities. This will give us a new angular velocity and hence a new sense of rotation along a new axis. But still it is very hard to visualise it.