A jewel smith wishing to buff a finished piece of jewelry attaches a buffing disk to his drill. The radius of the disk is 3.20 mm, and he operates it at 2.50*10^4 rad/s. (a) Determine the tangential speed, in m/s, of the rim of the disk.

(b) The jeweler increases the operating speed so that the tangential speed of the rim of the disk is now 285 m/s. What is the period of rotation, in seconds, of the disk now?