作者Yuchin1992 (QB( ● ω ● )Yu)
站内TransPhys
标题[考古] 几题台联...
时间Wed Jul 6 15:30:23 2011
考试快到了，所以把做了几年的考古题提问一下
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)
不太懂题目的意思，是指非协调的条件吗? 答案是(E)但我选了(C)
97 12.
附图：
http://i.imgur.com/1U1S0.png
完全没有想法，而且洞里面每个点的磁场应该都不太一样不是吗?
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) 但是不知道该怎麽用
而且学生都是理学院，所以偏工学院的单元教授也讲的比较少比较简单
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
也是完全没有想法，电感有电阻？还是指的就是X_L？
以上四题麻烦请各位帮忙，感谢~
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 123.110.174.112