Đề 3 Bài làm Điểm !"#$% &"' ()*+%,-()*+ %."/ 0"%12- 3" %."/3)/4-()*"5-()* %."/3-()*6"%4 "4-7)+8"' 9"4)+83:"$-( *;< $-( -/ 63 = > ? 1 %) @ -A @ "3 = ) @ 1 B C ? < D = - = @ @ -3 = @ ? CE9E F @ = G @ @ -3 = ? "-" @ 1 > = $H ? -1I = -A @ ) @ "' 9"4)+83:"$-( *;<$-( -/ ( ) 2 1 4 l k λ = + J"-H--K 9L<-()*< -()*+</9M3'3A> %NC G 9L 2 m T k π = ()* 1 2 k f m π = ()*+ k m ω = /9M3' 2 k F m x kx ma ω = = = GA>% 2 2 2 2 1 1 1 2 2 2 M W m A kA mv ω = = = OG$-"' N+ 9L P<Qs 3" Rcm GS*-T""U3V- W 3;-6K J x cm= -E"' A"-1A-6L "-1A-6L3V-* "-1A-6L"-* ()*+ 2 4 ( / )rad s T π ω π = = 0" 6 ( )A cm= ( ( ) 4 rad π ϕ = − A-6L 6 cos 4 ( ) 4 x t cm π π = − ÷ A-6L3V-* 24 sin 4 ( / ) 4 v t cm s π π π = − − ÷ A-6L"-* 2 960 cos 4 ( / ) 4 v t cm s π π = − − ÷ QX-"' N+ 1A-6L Q) O Y Z O x t cm π π = + ÷ K3V -*9"3V-W 3;-6K+-> ,J(> ;-6K+->,J(> 3 t ñ W W= ; V-[-A> t ñ W W W+ = \] 4 ñ W W= ) ]6 10 ( / ) 2 A v cm s ω π = ± = ± R\""' ^ 1 9 cos 2 ( ); 2 x t cm π π = + ÷ ( ) π = 2 9sin 2 ( )x t cm "-1A -6L-_71 + ( ) 2 9sin 2 =9 cos 2 ( ) 2 x t t cm π π π = − ÷ 41 1 2 ϕ ϕ ϕ π ∆ = − = 0" 1 2 0A A A= − = A-6L 0x = `X-)+-6 ]'"-8 a3:":)+ cm K 9[b-83;-6K+1 ( %)+ 2 x ϕ π λ = 'J6 J Y Z O rad π a X J O π ϕ = c ]6 4,5x cm= dX-)+-6 ]'"3:":)+ OPcm -6I]a"" P<em 3:"$-( *;<$-( -/ K)*U-)+W )b-7-6 I] "' 9"4)+83:"$-( *;<$-( -/ ( ) 0,4 2 1 0,9 (2 1) 4 4 l k k λ = + ⇒ = + c*$U")+ 4k = c*U-)+f 1 5k + = 'J6 . K3V -* 9"3V-W 3; -6 K+ - > ,J(> ; -6 K+ - >,J(> 3 t ñ W W= ; V-[ - A>. P<Qs 3 " Rcm GS* - T""U3V- W 3; -6 K J x cm= - E"' A" - 1 A -6 L