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Donut approaching the speed of light

  1. Mar 17, 2004 #1
    donut approaching the speed of light!!!

    okay so as bodies approach the speed of light their mass gets bigger and bigger, approaching infinity - and their volume gets smaller and smaller, approaching nothing - a things length will get shorter and shorter as it approaches 186,000 miles per second - in the direction that the object is traveling.

    OK - so lets say i had a donut that was spinning very fast, approaching the speed of light.... what would happen knowing that things squish in the direction they are travelling as they approach the speed of light?
  2. jcsd
  3. Mar 17, 2004 #2


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    I replied to this on PM, but I'll repeat it here. The classic problem that is similar to your donut is the spinning disk. Each circular section of the disk is moving at its own tangential speed relative to the unmoving center, and yes, they do contract according to the formula. The formula is nonlinear so the contraction can't keep the disk flat, but there is no vertical force on it to bend it. This is taken as an appearance of noneuclidean geometry in SR. The full discussion of the spinning disck requires GR. I presume the same applies to your spinning donut.
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