7. The equation of motion of a driven oscillator is written as

where m is the mass of the oscillator, kx is the restoring force, F is the amplitude of the driven force, and ω is the angular frequency of the driven force. In what condition the oscillation becomes out of phase?


(A)
(B)
(C)
(D)
(E)

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詳解 (共 1 筆)

#7445491
所以這題可以根據題目給的式子
x(t)=Acoswt代進去
所以d^x/dt^2可以得到
6a58840fc0799.jpg
所以根據選項來去討論正負
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那如果是等於的話,就是達成共振條件
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所以可以直接記住無阻尼振動的時候
6a588484d8d76.jpg
如果角頻率小於初始角頻率,則為同向
如果等於,為共振
如果大於初始角頻率,則為反向
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