彈簧長度L0 力常數為k

Let L be the total length of the spring.
Centripetal force (向心力) = m.L.w^2
Force from spring = k(L - Lo)
Hence, k(L - Lo) = mLw^2
kL - k(Lo) = mLw^2
L(k - mw^2) = k(Lo)
L = k(Lo)/(k - mw^2)