Periodic Motion
From WikiEducator
Periodic motion is motion in which the position(s) of the system are expressible as periodic functions, all with the same period.
FYI
Heres a link thats like an online interactive textbook. Will answer any questions you might have..: http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/wavestoc.html (dhic014)