式8: "C" Subscript, 2 , Baseline equals negative StartFraction, "F" "w" left parenthesis, negative "m" "w" squared plus "k" , right parenthesis Over left parenthesis, negative "m" "w" squared plus "k" , right parenthesis squared plus "u" squared "w" squared , EndFractionC2=−Fw−mw2+k−mw2+k2+u2w2
equals=
negative 5.0 5 8 1 7 6 7 3 8 2 8−5.05817673828
8
式9: "F" Subscript, "c" , Baseline left parenthesis, "t" , right parenthesis equals "F" sine left parenthesis, "w" "t" , right parenthesisFct=Fsinwt
9
式10: "X" left parenthesis, "t" , right parenthesis equals StartFraction, "F" left parenthesis, negative "u" "w" cos left parenthesis, "w" "t" , right parenthesis plus left parenthesis, negative "m" "w" squared plus "k" , right parenthesis sin left parenthesis, "w" "t" , right parenthesis , right parenthesis Over left parenthesis, negative "m" "w" squared plus "k" , right parenthesis squared plus "u" squared "w" squared , EndFraction minus StartFraction, "m" "g" Over "k" , EndFraction plus "e" Superscript, negative StartFraction, "u" Over 2 "m" , EndFraction "t" , Baseline left brace, "u" squared minus 4 "m" "k" greater than 0 : "C" Subscript, 1 , Baseline "e" Superscript, StartFraction, StartRoot, "u" squared minus 4 "m" "k" , EndRoot Over 2 "m" , EndFraction "t" , Baseline plus "C" Subscript, 2 , Baseline "e" Superscript, StartFraction, negative StartRoot, "u" squared minus 4 "m" "k" , EndRoot Over 2 "m" , EndFraction "t" , Baseline , "C" Subscript, 1 , Baseline cos left parenthesis, StartFraction, StartRoot, 4 "m" "k" minus "u" squared , EndRoot Over 2 "m" , EndFraction "t" , right parenthesis plus "C" Subscript, 2 , Baseline sin left parenthesis, StartFraction, StartRoot, 4 "m" "k" minus "u" squared , EndRoot Over 2 "m" , EndFraction "t" , right parenthesis , right braceXt=F−uwcoswt+−mw2+ksinwt−mw2+k2+u2w2−mgk+e−u2mtu2−4mk>0:C1eu2−4mk2mt+C2e−u2−4mk2mt,C1cos4mk−u22mt+C2sin4mk−u22mt
10
式11: "D" left parenthesis, "t" , right parenthesis equals "m" "X" prime prime left parenthesis, "t" , right parenthesis plus "u" "X" prime left parenthesis, "t" , right parenthesis plus "k" "X" left parenthesis, "t" , right parenthesis minus left parenthesis, "F" Subscript, "c" , Baseline left parenthesis, "t" , right parenthesis minus "m" "g" , right parenthesis left brace, "t" greater than 0 , right braceDt=mX′′t+uX′t+kXt−Fct−mgt>0
11
式12: "u" squared minus 4 "m" "k"u2−4mk
equals=
negative 142.0 7 6 7 3 6−142.076736
12
式13: StartFraction, StartRoot, 4 "m" "k" minus "u" squared , EndRoot Over 2 "m" , EndFraction4mk−u22m
