7. An object of mass m that is initially at rest slides down from the top of a smooth sphere (of radius R). If the size of the object is negligible, at what angle θ will it detach from the sphere?
(A) cosθ = 1/2
(B) sinθ = 1/2
(C) sinθ = 2/3
(D) cosθ = 2/3
(E) none of the above.
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統計: 尚無統計資料
統計: 尚無統計資料