Question 1155424
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First, the standard and common name for "a circular planetary ring" is "an orbit".


Second, to answer first question, divide  {{{2pi}}}  radians  (full angle, or complete angle, or one full rotation angle) by 190000 hours.


And finally, the linear velocity is the circumference of the circle (= the length of the orbit)  {{{2pi*R}}} = {{{2*3.14*135000}}} kilometers,

divided by the time of one rotation 190000 hours.


You do all needed calculations.
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