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Is a circle spinning near c still a circle?  

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  1. 1. Is a circle spinning near c still a circle?



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Posted

The equation of a circle [math](x-h)^2+(y-k)^2=r^2[/math] where (h,k) is the center and r is the radius. The equation of the circumference has no bearing on if it is or isn't a circle.

When a circle spins, the circumference shortens and the radius stays the same. Is a circle, spinning near c, still a circle?

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Posted
i want to see what the masses think about this. do you have a problem with that?

I don't see what the point of the poll is, seeing as it's not a matter of opinion, and the discussion itself is already underway.

 

I'm not interested in whether or not you think I have a problem.

Posted

Thank you. It hurt my eyes.

Now, I don't really believe what yourdadonapogos is saying. If the circle was spinning rapidly, the radius/diameter would too, so relativity would affect it too.

Just another reason...

Posted

I'm not sure if yourdad meant to say that the circumference was actually affected, or if it just appears that way to someone in a different relatavistic frame.

Posted

Oh, OK. But if the circumference only apears to be effected I don't see what the problem is. Then the circumference divided by the radius would still equal pi.

Posted

ok, if a meterstick is flying at a substantial fraction of the speed of light then it isn't a meter long to the outside observers. the circle works the same way the LENGTH gets shorter in the direction of acceleration. that means even if the radius wasn't a line, it wouldn't shrink in a way that affects its length. does that answer your question? i would put some BIG diagrams on here, but i don't know how.

 

maybe dave could reply when he gets back from his holiday.

 

edit: the circumference is shorter, circumference divided by radius doesn't equal pie. saying they are equal would be like saying [math]3/2=1/2[/math].

Posted

Oops...I meant to click yes...I don't know what I was thinking. I wouldn't think anything would change about a spinning circle, but I know a spinning disk changes...

Posted

i have come to the conclusion that since, it would still have the same equation, it is still a circle.

 

the definition of pi is the circumference over diameter, so i say that pi is not a constant.

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