内容正文:
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17
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1.B 2.C 3.D 4.C 5.C 6.D 7.B 8.C
9.AC 10.BC 11.ABD 12.AD
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T
4 =0.1s,
;
T=0.4s,
<=>45?λ=4m,@5Av=λT =
10m/s.
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15.
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t=2.5T,
C;
T=0.24s,
<>D34λ=120cm=1.2m,v=λT =5m/s,
x=50cm
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A
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t′= xv =0.1s.
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MLNO5'PQL
f=1.0×105Hz,
RS()T0UV
T= 1f=10
-5s
x=7.5×10-3m
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RS3
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.
(2)
MLNO5'PQL
f=1.0×105Hz,
<5'>D34NO5'5?
λ=15×10-3m,v=λf3;NO5'Ab
v=λf=15×10-3×1.0×105m/s=1500m/s
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x=vt2 =
1500×4
2 m=3000m.
17.
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x
7
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λ=4m,T=0.4s
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Rv,-wY
x=-1m
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t=Δxv =
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7
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xb =Acos(
x
λ
·2π)=5×cos(
4
3
4·2π)cm=-2.
5cm
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s=2A+|xb|=12.5cm.
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t1 =T+
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v= λT,C;v=5cm/s.
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<=>34
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T
A=2cm
Q
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t2 =
xQA
v =0.7s
Q
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y=Asin[2πT(t-t2)]
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t≥0.7s,,
y=2sin[5π2(t-0.7s)](cm)
t<0.7s
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槡 α,Oyz{|
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= Lcosα
,β=θ-α,}Xb~=d=
ABsinβ,w d= Lcosα
sin(θ-α)= Lcosα
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n2-sin2槡 θ
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