作者Yuchin1992 (QB( ● ω ● )Yu)
站內TransPhys
標題[考古] 幾題台聯...
時間Wed Jul 6 15:30:23 2011
考試快到了，所以把做了幾年的考古題提問一下
98 07.
The equation of motion of a driven oscillator is written as
2
d x
m ----- + kx = F cos ωt
2
dt
where m is the mss 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) ω < k/m (B) ω > k/m (C) ω < √(k/m) (D) ω = √(k/m) (E) ω > √(k/m)
不太懂題目的意思，是指非協調的條件嗎? 答案是(E)但我選了(C)
97 12.
附圖：
http://i.imgur.com/1U1S0.png
完全沒有想法，而且洞裡面每個點的磁場應該都不太一樣不是嗎?
96 4.
A wire is stretched form L to L+ΔL. The Young's modulus of the wire is Y and
the density of the wire is ρ. What is the speed of a transverse wave
propagated through the wire?
(A) √(YΔL/ρL) (B) √(2YΔL/ρL) (C) √(2Y/ρ) (ΔL/L)
(D) √(ρΔL/2YL) (E) √(ρΔL/YL)
有想到要用 v = √(F/μ) 但是不知道該怎麼用
而且學生都是理學院，所以偏工學院的單元教授也講的比較少比較簡單
95 13.
An inductor has a 54 Ohm reactance at 60Hz. What will be the peak current if
this inductor is connected to a 50Hz source that produces 100V rms voltage?
(A) 0.69A (B) 1.41A (C) 2.71A (D) 3.14A (E) 1.73A
也是完全沒有想法，電感有電阻？還是指的就是X_L？
以上四題麻煩請各位幫忙，感謝~
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