Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
When you spin the the disk, it moves in a rotational motion. The faster it spins, the faster it moves.
So far I must be boring you with those facts. But something else is happening (or not happening depending on your POV). As you're moving linearly towards the center of the disk, its motion is slowing down
(assuming the disk is maintaining the same rate of rotational speed). And as you keep moving towards the center, you're moving even more slower. Until you reach the exact center where the pattern shows you're not even moving at all! And it doesn't matter how fast that disk is spinning; its exact center never moves.
This seems to defy common sense. How could the entire disk spin while its (attached) exact center never moves? One way to resolve this apparent paradox is to deny the center.
Another situation which relates is the eye of the hurricane. Only that the closer you get to the center, the faster the hurricane is spinning. Until you reach the eye which doesn't spin at all!
For me it makes sense and I accept it as part of my reality even though it's theoretical (with respect to the spinning disk). How about you?
Hamlet:
And therefore as a stranger give it welcome.
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy. Hamlet Act 1, scene 5, 159–167
I hold a round bowl full of water with a four petalled flower floating on the water in the center of the bowl. Each petal is pointed to one of the four compass directions. I hold the bowl at arms length and begin to spin myself in a circle. The water in the bowl appears to be turning inside it but it is actually the bowl spinning around the water and the flower stays motionless in the water and the petals always stay aligned and pointing to the same compass directions they were each pointing at before I started to spin myself in a circle.
Who is the center of the turning disc? Is it me or is it the flower in the bowl that I'm holding at arm's length?
No.
OP is referring to what is called axis of rotation. Axis of rotation is represented by a geometrical dot. Geometrical dot has no dimension. It is infinitesimally small. Rotation is always represented by a radius moving about a center of rotation. As there is no radius for a geometrical dot, there is no rotation.
In lay terms, center of rotation is basically imaginary concept.
When you spin the the disk, it moves in a rotational motion. The faster it spins, the faster it moves.
So far I must be boring you with those facts. But something else is happening (or not happening depending on your POV). As you're moving linearly towards the center of the disk, its motion is slowing down
(assuming the disk is maintaining the same rate of rotational speed). And as you keep moving towards the center, you're moving even more slower. Until you reach the exact center where the pattern shows you're not even moving at all! And it doesn't matter how fast that disk is spinning; its exact center never moves.
This seems to defy common sense. How could the entire disk spin while its (attached) exact center never moves? One way to resolve this apparent paradox is to deny the center.
Another situation which relates is the eye of the hurricane. Only that the closer you get to the center, the faster the hurricane is spinning. Until you reach the eye which doesn't spin at all!
For me it makes sense and I accept it as part of my reality even though it's theoretical (with respect to the spinning disk). How about you?
Matter has dimensions. Therefore, no matter can exist solely at the exact center - some portion of that matter must extend out beyond the center even if it is just an atom.
If by exact center and nothing but then you are only referring to a dimensionless point, then this does not rotate - because it is not a substantial thing and is just a coordinate in space.
If by exact center and nothing butthen you are only referring to a dimensionless point, then this does not rotate - because it is not a substantial thing and is just a coordinate in space.
There is no paradox.
Ahem, as stated in my previous post... A center of rotation is IMAGINARY concept that is non-substantial and as such, can not rotate.
I also have to apologize. It is not geometric dot, it's geometric point. Same word in my native language.
So, center is a geometric POINT a point is defined only by some properties, called axioms, that it must satisfy. In particular, the geometric points do not have any length, area, volume, or any other dimensional attribute. A common interpretation is that the concept of a point is meant to capture the notion of a unique location in Euclidean space.
hence, such spacial/dimensional attribute as rotation can not be applied to point. Far as I know, LINE has no dimension too.
No.
OP is referring to what is called axis of rotation. Axis of rotation is represented by a geometrical dot. Geometrical dot has no dimension. It is infinitesimally small. Rotation is always represented by a radius moving about a center of rotation. As there is no radius for a geometrical dot, there is no rotation.
In lay terms, center of rotation is basically imaginary concept.
No, he is talking about the disc, a tangible thing. The disc is physical - at the center - it is rotating, even at the molecular level. The conceptual axis of rotation is irrelevant to "does the center of the disk" move. The center of rotation is not the center of the disk, the disk being a tangible object. No molecules, including the very central molecule (in fact molecules in the z-dimension since it is unlikely to be a single molecule thick), no disk. A disk = molecules. Does the center of the disk rotate? Yes. Does the axis of rotation rotate.... not the question.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
