giao an vat ly 12 da sửa -2011-2012

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− !""!
−#$!%&'$
!"
(%)*+ !,-.,/-"01
#$%&2345"/,5 6-"*"/7,8+-"

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,9
FJ74$K9: L,/5M8,N LC
FJ77/+7/>/
FO,-P>7/
-- 4%$!",Q/R
/0123456
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:;<=>?SW"TU9I)IX
#(;@
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%&ASAW"TU9J;:K9LK=*MN=%&O
/.90
"0""94%$!",Q

F(+.9H8$/)
4Y#1Z[[
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  8Y  \4    $  
14]
:4    >  ,-  C
$    $@  "  $  8
MC/!^
9X%0^
F_`DG#>
#1Z[[
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^
P-ab,C/>
44
Fc>#1Z
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
3DEFG
QN=%&OR
F(+.9:4>#1Z
[[\4F$
]
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#/,$+\f
3=%&KS
e/

M 1 @    f
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VD: e>Z[[
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$!
"0""94%$",Q
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$/@$K\/k
 +l,N,-8
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$K7@/
mW,7@/≠W^
FX7@/mW,
$+>/4?
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/4?
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Fj,$+>,-4
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Fj!%>Q
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:
A
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

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:=5$@A\4
e:1v\lr:T


b
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 
rf~#•7>,-
:#€@$
E
A
 L ,-aQ"d,$+\fC,$+
elr:T
pV@Nq,r,sSA"TU
F:\•dA%iF$‚FGHI
Fr-"ƒ‚„$„FGHI
 
4741


F9n…>
ns L""
F(%9n0$!>,1+7$"0$!
n:)*5M8 L,
n:)*,-,>
!"F(<[>h@,N"f )
Fs/-"0=RGHI
#$%&2345"/,5 6-"*"/7,8+-"

'()

$*+9:;!,</1=>!%>/?$@
A

B
:8
;+/-C+5/1/7DAEFGHI
,9
FJ74$K9: L,/5M8,N LC
FJ77/+7/>/
FO,-P>7/
-- 4%$!",Q
/0123456
7%89SB"TU9V$-= /$
:;<=>?Sƒ"TU


9…,,%"0$!^:%6,0,7$8


9: !
l@$7C"7g
r@ZQ$7C"7g
:@,-=5/
e:\r,:T

#
:6\sai
r>/,-K
l=7a
/a



 
rf#•7>,-
:#€@$
E
A
 L ,-aQ"d,$+\fC,$+
el:T
#(;@
tTKg,uUSA"TU9Chúng ta đã biết phương trình dao động điều hòa, vậy để xác định được
trạng thái dao động tức là ta cần phải xác định được vận tốc và gia tốc của vật.
t<TN,
1AB-CD.E/ E4FGCD6H
G30I
%&ASAi"TU9T;:K*vw*x=w%=*vN=yzy)Kx
9 D€4,%*,-
  $      
K^
†47,$+,
$+\  f ,- C8
,-%^
 >,-,
%,N">4
a^
,ma‡m−ωlSωnϕU
am±l
⇒
,mW
amW,m±ωl

P @8$f,-
$ˆ"π`B,N
//{m/YDmCD/{
3DEFGFXEY
/ug

US‰
ϕωω
+−==
tAxv
F,
/a
mlω amW9(-#(X:r
F,
/
mW am±l9(-R,$+
KL9(-$ˆ"π`B,N
 (%   * >  
US‰‰‰
B
ϕωω
+−=== tAxva
=g
  $      
K^
H,8C
/!^
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,N,8NŠ
5,NN>


US‰‰‰
B
ϕωω
+−===
tAxva
F‹‹
/a
mlω
B
 am±l9,-R
FmW amWS(X:rU 8
Œ

mW
FH)Q,NSD49
(b0)N,(X:rU
KL:H)),N
,8NŠ5,NN>
%&BSAB"TU9/|%}8j=N=%&%MK8=
FDNyD,<[a
,$$@"ϕmW
FImW9
amlSωU
mlS
B|
X
U
,mFlωS
B|

X
U
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•D
F(<[$@"ϕmW
 WX`EX`BvX`EX
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,
WFlωWlωW

Flω
B
Wlω
B
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B

lω
B

mFlω
B
S
B|
X
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Fj,-
7@/mW
mX`E
mX`BmvX`EmX

bjgfS•"TU
F:>7 %*,,-,>
FsP,<[>


?,-K #,$+\f8
l,-fW,=7 r,-=7,=7
:,-8N=7S=7U,fW e,-fW,fW


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lmω
B
a rmFωa
B
 :mFω
B
a emω
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!X7@/m
E
Xv
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9
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:,m lYmW e,mWYmW
pV@Nq,r,sSA"TU
F:\•d•F$„FGHI
Fr-"AWAA$„FGHI
F:-"R-"
a
,




X
2
T
4
T
4
3T
k
k
k
l
Fl
ω
A
Flω
Flω
B
lω
B

k
k
479
474
#E€•€•‚E
[+K9
1. Kiến thức
F(%9:)*= b,.,,-KY:)*+ !>ZK
aY:)*+'%',0'>ZKa0'1
FH1+7>ZKaK
F-ab+,=%',%' Z
FŽ".)*,-8$-"1-"0=
F(%"0$!=6>ZKa
2.Kĩ năng91-",4>Z
3.Tư duy và thái độ9:8 1'4ˆ64--*T, 6*.
6,=
Kƒ>8
$*+ZKa*,8%p!,<
,nJ7"0$!K*,,-
nJ79'%'0' 5/=[%'[
-VOU$UN,/7/R,Qh,56
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7%8Q@U
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FX$1@\•A%•$ƒ‚„GHI
#&NK>;@
Hoạt động 1: Tìm hiểu cấu tạo con lắc lò xo và trạng thái của con lắc^pUc`
%&/ %&H &NK
oH(Dah/!,<=
5\59

FQ7>ZKa^(X:r
>8
FI b,-%r1h•
#//)14
>Z^
Fe>Z8"1
K ^
oG41-=
5\5>H(

Q„QW\
1. Cấu tạo: [//,-• 
/Z,/Ka 

Nhận xét: b,-%,$+r1
= )/Z
K#,$+\f
Hoạt động2: Khảo sát dao động của con lắc lò xo về mặt động lực học, chu kì, tần số^pUc`
oZ7N1
=6^
o(<!/)1$7>
ZKa^
F_   665 #
%"\+=,Š$•=
\4$4>Z 
Ka€%7^
oDNyDG*•
ZK•

o:=55:

A^
o(% )* +    !
>Z^
oDG41-$1@
oDG41-$1@
tX1-:
A
tX$1@h4
$N=%&j=Q„QW
\*M;…%8QV†
Ib,-/%r1,-=
•#/!,-N
.>=[ŒmF a
Xh-‘‘089
Œm/
⇔
’ am/
⇔
mF

/
a
C9ω
B
m
k
m
⇔
mFω
B

a85/
amlSωnϕU/uQ„N=%&
%MKW=
oX, !,>ZKa9
Tần số góc:
k
m
ω
=
k
a
Œ
r
Œ
r
x
?
l

ur

ur

ur

ur
o\ab,N,N
>= b,
F(%)*>= b,
,-ab=,+5/

C hu kì:
B
m
T
k
π
=
tLực kéo về
Fs=))N,,$+\
f
F8NŠ5,N
Hoạt động 3: Xây dựng biểu thức động năng thế năng , sự bảo toàn cơ năng^pUc`
* Nhắc lại các vật chuyển động
dưới tác dụng của các lực thế;
lực đàn hồi, trọng lực thì cơ
năng bảo toàn
* Trả lời các câu hỏi sau:
 P   )  *  +  '
  > ,- 8    4
^
F     )  *  +  '
>,-8 %
7^
F:0'>,-
.>%1
€4  /  *  7    ,N
$@ "  4    >
Z^

F2T$ %-,0'>

Z$

FD\•:
B
^
oDG%"N7 %*
oHN$1@)*+
',%'
PDG=/"1 /
*d)*0'
Fe=,)*4$ %
-
FD\•:
B
$N=%&j=Q„*M
;‡"QV†
1. Động năng của con lắc lò xo
B
A
B
d
W mv=
2. Thế năng của lò xo
B B

A A
t
B B
k l kx= ∆ =
3. Cơ năng của con lắc lò xo . Sự bảo

toàn cơ năng .
B B
A A
B B
d t
W W W mv kx= + = +
?9“

m
A
B
/,
B
m
A
B
/l
B
ω
B

B
SωnϕU
,N mω
B
/
“

m
A

B
a
B
m
A
B
l
B

B
SωnϕU
m
A
B
/ω
B
l
B

B
SωnϕU
Suy ra:
B B B
A A
B B
W kA m A
ω
= =
= hằng số
F :0  '>  Z  Š 5  ,N !

"0>
F:0'>Z1%
R#/6/ .
bjgN…NW^pUc`
PH,8/7+>I/$/*-*,%"/N>6f/
\X$Z5/7$N
F(3/-"9Ei•G `Av
5. Rút kinh nghiệm :
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]



P:>, Z\/ %*,K
F_6Z79…"0$! !,-,[
>K
!"
(-. %*€6,1-"8#
#$%&92345/,5/T 6-"*"/7,8
+-"
'()
$*+9
:;5-",K8Ny1
,9
D6g,/-"
-- X4%$!",Q
/E4FG3456
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$*+ :Z,N08•.!,<
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-VOU$UN,/7/R,Q,56
/<TN
7%8Q@U
:;<=>?(5phút)
= :\•Bv$AvGHI
> :\i•$AvGHI
#(;@
FT;:KQ„%O*M‹K*<$j=i(5phút)
%&/ %&H &NK
oH(Dah/!,<$1@
\•
FQ7>Z0^
FI b,-/%r1š•
#//)14>
Z^
Fe>Z8"1
K ^
oG41-=
5\5>H(
QQ„%O
1. Cấu tạo:/,-•
8 /$hR

/\4 )
€ 
Nhận xét: b,-%,$+r1
= )/Z0
K#,$+\f
%& $N=%&j=Q„%O*M;…%&Qr,(15phút)
oZ7N1
=6^
o(<!/)1$7>
Z0
F_665#%
oD,<!41
- = 5  \ 5
>H(
$N=%&j=Q„%O
*M;…%&Qr,
oI/R,$+r!9
n(-Cak?mm
α
n($+\4$haR8
α
9
s=l
E
αŒ•

D
_
αŽ•
T

ur
n
P
uur
P
ur
t
P
ur

(

"\+=,Š$•=\4$
4>Z0h
"0+f)*
^
oDNyDG*•
Z  0 8    ) 
K
o…C,Q 5Z
0^
oG)*

mF/`
,ŒmF a(%)*+
 !>Z^
o:=55:
A



:
B^
oX$1@hP
o:*/Z0

oG,$Kp /`
$T$)*+
8, !>Z0
oX$1@\•:
A


:
B
os=\4$4,=
N\/9

mF/α
m›e…>Z0 )"1e……D
(Nα
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AW
W
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

mF/`
(-43=%&j=Q„%O*@i
QŠ ‰  Q  N=  %& %MK   •
UVO<T]

•
^ω_ϕ`
*@
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>+%&N=%&
oX, !,>Z09
Tần số góc:
l
g
ω
=
Chu kì:
B
g
T
l
π
=
%&#$N=%&j=Q„%O*M;…"QV†(10phút)
* Trả lời các câu hỏi sau:
P)*+'
>,-8 ^
F)*+'>
  ,-  8    8 R  $  $6
$d0^
F:T/0'>Z
1%•#/^
oX$1@\•:

v

oHN$1@)*+
  '  ,  %  '  ,  0
'
tX1-$1@
 $N=%&j=
Q„%O*M;…"QV†
1. Động năng của con lắc lò xo:
B
A
B
d
W mv=
2.Thế năng của con lắc đơn
SA  U
t
W mgl
α
= −
3. Cơ năng của con lắc đơn
B
A
SA  U
B
d t
W W W mv mgl
α
= + = + −
%&b+KN[j=Q„%ON‘%:\$%8=g<OrN(5phút)

o  ) . >   Z
$,=Q
o…/(e=%Q4
).>Z
o\+4\y%
84&RM
0 p
oDZh%" %*
oD8p1N""\+
=4&>
/IN[\$%8=g<O
[N
Xd
B
l
T
g
π
=
]Œ
B
B
E 

X
π
=
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oX!//,+.
f”i;=$Q„N=%&
%MK*@Sg<+^Sg•U[
K&*$%…Zj=Š`
3=%”„NS9
1. Thế nào là dao động tắt dần ?

Dao động mà biên độ giảm dần theo
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2. Giải thích :
e=1>/)$@SŒ
/
U/
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⇒
l1/,d7
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r"-1/a8 ))ah/4"-
•=]
3=%&NK<T
t 3=%&%V†NK<T>–$—
 >+%&  f”  %9  ;  f”  Q;
=%9KfTN=%”<+j=Š,
QN=%&NK<T
o(+.,4$!9
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E
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Hoạt động 2: Tìm hiểu dao động cưỡng bức(10 phút)
ĐVĐ: ?@d#4
14a
o-ab>
#4T4%^
o  ?        #4  ,y

W
 Z!@T
/!^
oH($œ*
)=4Q"/
s#4p7s/Q
//

os/X!EvS:
A
U
oD6-ab>#4
oS.7=U@p
4;4
DG%"N

oD\•:
A
3=%&V˜>
QN=%&V˜>
n3=%&8K$N[j=;&
QrV˜>KS,QN=%&
V˜>
/ZN[9GHI`A„
#F…%:;9
nŠN=%&V˜>iSg>–
Sgj=QrV˜>
ni>+%&f
•
%9,".,9
Fr>7=
F…5>7=x,N
$>5x
W
nIxfx
W
 !
œ*%&N

%&#T;:KŠV†&VshrVsj=&Vs^•Uc`
o:6>
œ*
o  HN  5  [    >  
œ*
oH1‘+
oX=55:
B
o\+/#$6>
5R.
8,7>R•
tD6
tX%" %*
tD\•:
B
tX1-8/$1@\•
>H(
/ŠV†&Vs
1. Định nghĩa: Š  V†>+  %&
N=%&V˜>"%$<8
r%fSg™j=QrV˜>
%Sg™
•
j=ŠN=%&,
QŠV†&Vs
FMKfŠ&Vs™mx
W
2.Giải thích:
Ixmx
W


⇒
5Q"'
"TT
⇒
5
'7=7 
'fQ"'

#S;LK=<,j=ŠV†&
Vs9
Fj-4= ah )
5.=œ*
/78xmx
W
y%€4)$!
FD" ,) 8" )
R
bjgN…NW^pUc`
PX8/Z7+f\•
X%Z1+7Z^eœ*^D5
R
\54$!,œ*^
F(/-"ABvEi•$BAG :;
p1cfŠ;

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Hoạt động 19 giải bài tập trắc nghiệm(20phút)
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- Câu 4 trang 13: D; Câu 5 trang 13: D
Câu 6 trang 13: B
-Câu 4 trang 17: D ; Câu 5 trang 17: D
Câu 6 trang 17: C
BA:\lYBv:\eYBE:\l
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Hoạt động 19 Giải bài tập tự luận về dao động điều hoà của con lắc lò xo và con lắc đơn (15phút)
Bài 1: ?,- b5 •
(X:r/7•/1,\
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( Một lò xo được treo thẳng
đứng, đầu trên của lò xo được giữ
chuyển động đầu dưới theo vật
nặng có khối lượng m = 100g, lò
xo có độ cứng k = 25 N/m. Kéo vật

rời khỏi VTCB theo phương thẳng
đứng hướng xuống một đoạn 2cm,
oDG%"
o…68/Z
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oDG
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
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am•S|n”U
mWamW,›W
am•”mW
,mF•|”›W
”mW
”¡W
m›”mF|`B
(-4"$!9am•S|’|`BU/
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 ”›W
 m›”m|`B
(-4"$!9am•S|n|`BU/

=`X7,$+\fk! ∆m/
⇒∆m
0,04
25
0,1.10

k
mg
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W
WS(X:rUU
a
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¢
¢
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W
W(VTCB)
a
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⇔
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⇔
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truyền cho nó vận tốc
310

.
π
(cm/s) theo phương thẳng đứng
hướng lên. Chọn góc tg là lúc thả
vật, gốc toạ độ là VTCB, c dương
hướng xuống.
a. Viết PTDĐ.
b. Xác định thời điểm vật đi
qua vị trí mà lò xo giãn 2 cm
lần thứ nhất.
* Hương dẫn Học sinh về
nhà làm câu b
o…68/Z
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nωm
π===
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1,0
25
m
k
S2`U
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amlSωnϕU
mWamB/›W
,mAWπS/`U¡W
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m›ϕmA`
v

⇒ϕm|`vS2U→lmES/U
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F(/-"$-";
p1cfŠ;
ngày soạn
ngày dạy
š 7A-D3DEFGF•D›
-h›lHm
-- œF~/•Ež1•P•
[+K9

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FZ/"0""1[Œ$hFh
Fr%!)*+&"l,5"ϕ
FZ/ p" 5"
“"G•.1[,h0#4&"BKp"0p
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#VNK*$%&9:8 1'4ˆ64--*T, 6*.
6,=
Kƒ>8
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7%8Q@U
:;<=>?9^pUc`
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Iœ*7$=7=74".,4%^

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%&/ %&H &NK
oZ7‘>,5M
      ,4
$K
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MO
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x x x= +
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A
ml

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8
%&#;Dh *9†UF&QŠU=^pUc`
oX)*+l”
oe=,!,<!/7
)*l,"
” >&
"S:
B
U
oI ϕ
B
 ’ ϕ
A
 mBπ !
a
A
,a
B
^lm^
oIϕ

B
’ϕ
A
mSBnAUπ!
a
A
,a
B
%
^
m›lm^
oI ϕ
B
 ’ ϕ
A
 m π`Bn π !
a
A
,a
B
%
^
m›lm^:%P>
5"^
tDNy/-"(e
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o4-ab
oG4-ab

tD4$1@
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os11
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=N=%&
Biên độ:
l
B
ml
B
B
nl
A
B
nBl
A
l
B
Sϕ
B
’ϕ
A
U
Pha ban đầu
A A B B
A A B B
l  l 

l  l 
ϕ + ϕ

ϕ =
ϕ + ϕ
3. Ảnh hưởng của độ lệch pha:
o%ϕ
B
’ϕ
A
mBπ9p
"m›lml
/a
ml
A
nl
B

o%ϕ
B
’ϕ
A
mSBnAUπ9
"m›lml
/
m
l F l
A B
n% ϕ
B
’ϕ
A 
mπ`Bn π9

,)8,N9
lm
B B
A B
l n l
b/ZN[9
:BK9
A
vSi US Ux t cm
π
=
,
B
ESi US U
v
x t cm
π
π
= +


A

B
a
ϕ
∆ϕ
?
A
?

B
?
E
4
A
4
B
4
4
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91
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X!/    &  "  v  

oX%"N X!/"0$!&"a^
H1
B B W
v E BvE•W •W‚ •AA cm= + + = ≈
W
W
W E •W
 W•„B‚ WA„
v E•W
ϕ ϕ π
+
= = ⇒ =
+
(-49am•ASi
WA„ US Ut cm

π π
+
bjgN…NW^pUc`
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F(/-"9ABvEi•$BiGHI
/1cfŠ;
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Kƒ>8
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Câu 4 trang 17: D
Câu 5 trang 17: D
Câu 6 trang 17: C
Câu 6 trang 21: D
Câu 7 trang 21: B
$Bi
oX&*78/1
-!/$"
o:D$!4d\
oX1-!/$ %#1
oD1+
Câu 4 trang 25: D
Câu 5 trang 25: B
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A

,a
B
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F(%"0$!&#9am
lSinϕU
FX!/l"
”&"
oI%-
Bài tâp thêm: :
p"0p9
(%"0$!&
">f9
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A
Frˆˆa
B
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ohNy,/
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A
a
B
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/CmQua tiết bài tập này chúng ta cần nắm được
Fr&"fv9,-.)*1[Œ$hFhp%&

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P(ah/7-",ah/$*0/N
F(/-"$-"
/1B£


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•rœEH.¤£
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
1. Kiến thức:
F-$8"0""p"5$/-(-P8"0""4ˆ6
,"0""=5/
Fr%p"0""=5/a=".> !X>Z0".
,>Z%

F-, !>Z0•Sα<AW
W
U
2. Về kĩ năng:
Fs=6Z+"%+5/
Fs=6[[@,=+"=5a !
>Z0,NŠdB£%E£
FX7+5/
F:8 '-",a•+5
'()
1. Giáo viên9:;/¤8/6SE→•8/U9
Fr#1\88/8$hiW
F…[[Q/\458•Q%WWA
2. Học sinh:
F…6$N=
FX$1@\•
F ¥$NR1•AS FBƒU
012345¥6
1. Kiểm tra sĩ số:
2. Kiểm tra bài cũ (kiểm tra sự chuẩn bị của học sinh).
3. Bài mới:
<†cUj=$*+ %&j=,
Hoạt động 1. Đặt vấn đề vào bài
FH,$@!/$->
Z0
F:846$1@/\•9
ne=ah/ !>/Z0".
,M7CC$l/α
%^
n: !>Z08".,0

/!5/^s/%"58
n:8 !Z08l¡AW/

\%"N
FX1-8/75$1@\•
>H(
I1=".> !
>Z0,d7
!Š784&4%
4 )^(!^   )&
nepZ4Z< %#1+a
0 a$0=70/X^
ns/a !X,N∆Xm
WWB p[[8 /\4^:% p
[[4±WBS[/>#,
..U
F:6@>
"
F(! ,N[[Q/\4
f&>..,>
#>@∆m∆XmWWB
nWBmWBB86›BW

%& ‚$%8<Trr
F_6a$!=N
=,M/P$d
N
FX$B•.Z8 
%^X$v^
F:6Z8%

+"^:Z^
FX1-8/75$1@\•>H(
(V@9I11R>
,N !>Z0
( 9I11R> Z
/,N !
(#9I11R>Z,N
 !
(b9Xd %#1$T$ %-
p¦.a$6$@
70/+5/
%&#$Vsj=>+%&N=%&*@KfTj=Q„%O
F_758/N%
+5/
n:=,NZ08
%$^
n:a8αdl^
X+α,4$85α$1•A 
FD€4a"/Z
=5^
HP9›BW
FXd %#1€4"-,
 !>Z0,N•^
FX1-8/75$1@
n…@>8α 
njα9αm
t
A
n…)@=5vW"
,N 

F:8/%h$!=N
F: !X>Z/f*•
8 )".,
4. Củng cố luyện tập:
FH(-ab@6
FDG6..=
5. Hướng dẫn học sinh tự học ở nhà:
F…6$N=%"h
FD4>4$1@+4%,@=h/yR 


1. Kiến thức:
Fr%p"0""=5/a=".> !X>Z0".
, />Z,Z%
F-, >Z0•Sα<AW
W
U,-,>
Z0
FXd=5/a)*, !>Z0
F¦.+$6$@70/+5/
2. Về kĩ năng:
Fs=6Z+"%+5/
Fs=6[[@,=+"=5a !
>Z0,NŠdB£%E£
Fr%=, %#1a•+5$T$ %-
F(<[XmxSU,X
B
mxSU
FX7=
'()

1. Giáo viên9:;/¤8/6SE→•8/U9
Fr#1\88/8$hiW
F…[[Q/\458•Q%WWA
2. Học sinh:
F…6$N=
FX$1@\•
FI¥$NR1•BS FBƒU
F:;§@Q4),<[
F:;$N1=h/y$GHI
012345¥6
1. Kiểm tra sĩ số:
2. Kiểm tra bài cũ (kiểm tra sự chuẩn bị của học sinh).
3. Bài mới:
<†cUj=$*+ %&j=,
Hoạt động 1. Khảo sát ảnh hưởng của khối lượng con lắc m đối với chu kì T
oH(46$1@\•9
F:=,NZ08%
$^
FG•.#1C%^
FX%%^G"/
Z^
oH(8/$R-..+5/
:TP9I4&#1C,y"1M4
>\4$h

oDG$1@\•,€
$
FeM4Z0
FX4&#1CSiWAWWAiWU
F:=5AW"

oDG%,1
•B$T$ %-9: !X/f
*•8 )"., 

Hoạt động 2. Khảo sát ảnh hưởng của chiều dài con lắc l đối với chu kì T
oH(•9
F:=Z08%
$^
F:8 !Z08¡AW/
 )^X7^
oH(48/=hN
FD€4+!"0 !X
A
B
X
B
B
X
v
B
,Š
9
B
B B
v
A B
A B v
 
T
T T

l l l

FD€4,<[ˆ=".>X,>
Z0,$T$-ab
oDG$1@\•/,4

FX4&
FI)(! 8 87$
,N•Y,! !X 8
o:8/-5/,.98/
$R"\)),5
,$8/
X%,51•vGHI
F(<[XmxSUQ4X )Š5
,N
F(<[X
B
mxSUQ4X
B
Š5,N
FD€4,<[ˆ=".>X
B
,>
Z0,$T$-ab
F2T$ %-9: !X>Z
0".,>Z
Hoạt động 3. Xác định công thức về chu kì dao động của con lắc đơn
Xd[8X
B
m

B
m (N )&!
Q4$fX∼
g

FD€4a\4=*+X=,
,$6$@Sπ≈„‚ƒ≈U
F(!π
B
≈„‚ƒ⇒
B
A
„‚ƒ
π
=
⇒X
B
m m
B
g
π

FD5 70/XaQ"aŠfE
⇒Xm
B
l l
k l k
g g
g
π

π π
= =
Hoạt động 4. Ứng dụng tính gia tốc trọng trường tại nơi làm thí nghiệm
Fe=, %#1$€4+$>
7/
Xm
B
l
g
π
G4$mEπ
B
B
l
T
4. Củng cố luuyện tập
F-, >Z0•Sα<AW
W
U,-,>
Z0
FXd=5/a)*, !>Z0
F¦.+$6$@70/+5/
5. Hướng dẫn học sinh tự học ở nhà
F(%="
F…6$N–G80,=$40—
47
474
VOHiO*iˆ;
 P#HiO*r<KMiO



F>80
F 5/#,N89868$48
 !N8"
F(%"0$!8
FC$>8 !4N8,'8
FX=/+5/,=$48$/\4
!"H1-"01,80
#VNK*$%&9:8 1'4ˆ64--*T, 6*
.6,=
'()
$*+:+5//)1,886,=$4>8
,J7,
-VOU$UN,/7/R,Q),56
/<TN
%&(5 phút)9:;<=>?
%&j=/ %&j=H &NK
F:;\•,e FX$1@h4
%& (35 phút)9T;:K*ZŠ;*MiO
%&j=/ %&j=H &NK
F?)1+5/,%+
5/!ƒA
FX$1@‘\•‘:
A
^
F…80^
FI88$/CNk?
^G8$4dk%?h
"0^→G8^
F?)1+5/,%+

5/!ƒB:8-ab!)
#+5/,!,<^
F…86,/)
$@$4
FDG# %#1+5/
FD:\:
A
FX%"N
F… 5/8
/)$@$4
FDG# %#1+5/$1
@
F… 5/86
/)$@$4
HiO
AX+5/
?gG0/CN
$→?,yQ
G,d7/,/CN7k
$→?

Vậydk€$4#
NN?
B…
FG80=$4>
$//)$@
vG8
Fs80$8"0
S>Q/abU⊥
,N"0$48

EG86
Fs80$8"0
``SC$pU,N"0
$48
%&p(5 phút)jg*N…NW
D7>H( D7>DG 
F:> %*$6\/
F_9DG/-",;

F:TPh•
Fs/-"M;

/1cfŠ;

(¦Hn/YH¤15XHn^U•`
/<T>N
%&(5 phút)9:;<=>?
%&j=/ %&j=H &NK
F_$1@‘\AB•ƒ$EW FX$1@‘h4
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5/,# %#1
+5/
FDG %#1#
d+5/
FX$1@\:
A
Hr==j==i;…
V@
`ZŠ;
FH•š$
⇒
$
/CN8M8&
!@4"h8/
G
A
G
B
`Z
FM@,N
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yU
FM@,N
=*4SB8C"
$5yU

F:88!@
4"h6,\
%& (15 phút)9T;:K*Mr%*r:K==
%&j=/ %&j=H &NK
F%"0$!87G
A
,G
B
9mlω
→0$!/¤87?
G
A
,G
B
R%8*
%^
Fe&"7?8
*^
FDNyDG&B,
+
   2
2 2
α β α β
α β
+ −
+ =
F-ab,X&"7?,
&"l
?
^

F?,N=7 
^
• mW
⇒
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A
m
B
c•+
@$$=>G
A
G
B

B
1
1
d
t
u A
T
π
λ
 
= −
 ÷
 
B
2
2

d
t
u A
T
π
λ
 
= −
 ÷
 
Fm
A
n
B
FDG/hNy>
FG4$1@
FDp"
Bk
ϕ π
∆ =
m
B
d
π
λ

⇒
r%*r:K==
Ar*7//?
$,p

F:B[G
A
,G
B
8pxp
"9
0$!7B[9

A B
B
 
t
u u A t A
T
π
ω
= = =
Fjb/?G
A
,G
B
/79

A
mG
A
?,
B
mG
B

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A
%?9

A A
A
B
 S U  B S U
M
d dt
u A t A
T v T
π
π
λ
= − = −
F0$!8dG
B
%?9

B B
B
B
 S U B S U
M
d dt
u A t A
T v T
π

π
λ
= − = −
FG8&"7?9
B B A B
S U
B  B
B
M
d d d dt
u A
T
π
π
λ λ
− +
 
= −
 ÷
 
(-49
Fe7?,y/
,N !X
Fr>7?9
B A
S U
B 
M
d d
A A

π
λ
−
=
B($+=7,=
Những điểm dao động với biên độ cực
đại S=7U

B
’
A
m λ(N mW±A±B]
G
A
G
B
H

H

F?,N=
^
B A
d d k
λ
− =
FD"
SB AUk
ϕ π
∆ = +

m
B
d
π
λ

⇒
( )
B A
B A
B
d d k
λ
− = +

Những điểm đứng yên, hay là có dao
động triệt tiêu S=U
2 1
1
2
d d k
λ
 
− = +
 ÷
 
(NS mW±A±B]U
%&#(10 phút)9T;:K%MKfŠir==*f$Š;if†U
%&j=/ %&j=H &NK
FD8 C"7?8

))C'@y
C$5yL
,
2 1
2 1
2 ( )
2
d d
π
πδ
ϕ ϕ ϕ
λ λ
−
∆ = − = =
M
87?
FH(9X$!4…I8
FD:\•:
v
^
FDG-,5"
5
FX%"N
FD:\•:
v
^
ŠV†==
• FMKfŠ9Hai sóng nguồn kết
hợp
Uep"0p


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
• Hai nguồn kết hợp phát ra 2 sóng
kết hợp.
• Hiện tượng giao thoa là một hiện
tượng đặc trưngcủa sóng .Quá
trình vật lý nào gây ra được hiện
tượng giao thoa là một quá trình
sóng .
%&b(5 phút)9jg*N…NW
%&j=/ %&j=H &NK
FF)*a,$+
=7,=^
F… 58^
F_9DG/-",
;
FX$1@‘h4
Fs/-",M
;
/1B£
479
4749
pBÀI TẬP
[+K9
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