The diameter of a long playing vinyl record is 12 inches. The unused center has a diameter of 4 inches, and there is a smooth outer edge that is 1 inch wide. If there are 91 grooves to the inch, how far does the needle travel within the groove during playback of the record?

The needle travels just 11 inches, from the outer edge to the center.

Posted by e.g. on 2005-03-30 14:43:32