4. A pendulum is formed by pivoting a long thin rod of length L and mass M about a point on the rod. Apparently, the period (T) of this pendulum (for small oscillations) depends on the position of the pivot. Suppose the pivot is at a distance d from the center of the rod. What d would give a minimum T? (The moment of inertia of a thin rod about its center is ML²/12)
(A) L/√6
(B) L/6
(C) L/√12
(D) L/12
(E) None of the above.

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統計: A(0), B(0), C(1), D(0), E(0) #3858160

詳解 (共 1 筆)

#7432806
所以這題和普通單擺不同的地方在於這題考的是實體擺
6a4c63546b141.jpg
6a4c635d57fcd.jpg
所以T^2會正比於
6a4c637fe1930.jpg
要使其最小化
6a4c63a2aca55.jpg6a4c63bb5cdd9.jpg
或令其最小化可以直接令其一次微分等於0
ㅤㅤ
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