THI LÝ L2-2011( ĐÀO DUY TỪ-HN)

:_
.,*
Trua/'ng
THPT'
Ebo Duy
Tl}
-
FIh NQi
Dd
thi thfr
dai hoc ldn
2
(ngdy
z8,lLLl}Arc)
Mdn:
VAt li,
khdi A
(Thoi
gian
tdm
bdi: 9A
phfi,
khing
*d tnA
gian
ph,ir
de')
Ma dd thi:201
CAu 1.
Cho
hai

dao d6ng
didu hol
xr
=
4cos(20nt
+
nl?)
(cm)
vi
xz
=
8cos(20nt
- 5n16)
(cm).
Bi€n
dO
vI
pha ban
ddu
cfia dao
d6ng
tdng hgp
cfra hai
dao
ddng
tr€n bdng
A.A=+.E(cm);
e=
0
B.A

=4Jt(cm);q
=5x16
C.A=4.5
(cm);,p=r
D.A=+J7(cm);9=2rcl3
CAu
2. Chon
c6u dring.
S6ng
si€u
im
A.
lan truydn
voi tdc
dd
l6n
hon
s6ng
h+
arn.
B.
lan
truydn
trong
chAn khdng
vdi
tdc dQ
ldn
nhdt'
C

fftl lan
truydn
f,ong
nudc
Uien
aE s6ng
kh6ng
ddi.
D.
c6 tdn
sd l6n hdn
2ffi2.
Cflr-s
3.
Trong thi
nghi6m
I
Ang, kho6.ng
cdch
giita}
khe
sri.ng
lh 0,2mm,
Khoing
c6ch
tt 2 khe
ddn min
li
1m'
Chidu

vlo
khe
S
chirm 6nh
sdng tring
c5 budc
s6ng
nim
trong
khoing
tit 0,38pm
ddn
0,76im-
T4i
vi tri
cdch
vin
sdng
chinh
gltra2,5cm,
sd
brlc x4
cho
vAn s6ng
trilng nhau
t+i d6
id:
A.5
8.8
c.6

D'7
Cdu 4.
Trong
crich mlc
m4ng
di6n
xoay
chidu
3
pha, ci mriy
phdt vi tii
ddu
mic kidu
hinh
sao
thi
A.
dbng
di€n
tr6n
diy trung hoi
lu0n
bang
0
B.
di€n
6p
gifta
day
pha vi dfly

trung
hoa
l6ch
pha
2nl3
so
v1idbng
di€n
C.
c6.egia
tri higu
d+ng
cta
cubng
AO
aOng
diQn
trone
3
pha bing nhau
D.
dien-6p
trigu
aqng
g-ira
day
phi vd
day
irung hoi
nh6

hon
di€n dp hiQu
dgng
gita 2
d|y
pha'
Cau 5. nagt
dog
hinh
tru diri 60cm,
dua
mot'am
thia
lai
gdn
migng
dng
vi
cho dao
dQng
vdi tdn
sd f
=
1360H2
rdi
ad
adn ouo"
va-o 6ng, kti
chidu
dhi cQr

nudrc
thich
hqp
thi
& migng
dng nghe
thdy.ary
le'
to nhdt,
khi
d6 trcng
dng
c6 s5ng
dilng
vdi m4t nudc
1l mdt
ntit
t6og
vd miQng
dng
li arQt
bgng
s6ng'
Bidt
loc
dQ. tru.ydn
ayiyn8
kh6ng
tilif^
S:,agn/r.

Khieb nudc
ddn d3n
ddy On!
tni c6
bao
nhicu
leo
nghe
duoc
am & miQng
dng
li
to
nhdt?
A.4ldn
B.
5
ldn
C'
6ldq
D'
T ldn
C*nr 6.
Bidt hai
dao dong
didu hoh
lu6n
nguoc
pha, didu nio
sau

day ld
khOng
dting?
A. Hai
dao dOng
c6
cing
tdn sd.
B. Hai
dao
dOng c6
c[ng bi€n
d6.
C. Hai
dao
d6ng
c6
pha
hon
k6m
nhau
sd
16 ldn
n.
D. Hai
dao
d6ng
c6
li
dd trr4i

ddu
nhau.
CAer T.
Cu6n
so
ctlp cfta*gt n
ay
bidn
6p ha
6p
c6 1200
vdng.
DiQn
6p
xoay
chidu
d{t
vio cuOn
ss
cdp
c6
gi6 ti
hi€u
dung
u
=
i00
v. Theo
tiah
to6n

rhi
dien
di
hi€u
dung hai
ddu
cuQn rhrl
cttp d€h6
h
60 v,
nhung
vi c6 mQt
sd
vbng
day'cria
cuQn
rh*;ap
quao ,n.o
ciridu'nguoc
14i
so
vdi
da sd
vdng
cbn
lai
n€n
diQn
6p hi€u
duirg

cfra
cu6n
ttrrl
cdp"chiia
+O
V.
86
qua
*qiluo
phi cira may
Uidn 6p.
So
vdng-lay
qudn
nguoc
bang_
-
4.60
vdng
b.
lo
uong
c. 120
vbng
D.240
vbng
CAu 8.
Can
crl
vlLo cdu tao

cfra
m5y
quang
phd,
c6
thd ndi
A. M6i
vach mhu
trdn kinh
enh
lb.
Anh
don s6c
cira thdu
kinh'
B.
M6i
vach mdu
tr€n kinh
6nh
li
Anh
don
sic
cria
ling
kinh'
C. M6i
vach
miru

tr€n kinh
anh ld
Anh
don
sic
cira khe F
cira
dng
chudn
truc.
D.
Ce
A,
B,
C
ddu dring.
Cau
g.
rvrEr
.oo'16" ld xo
c6 chidu
ctdi tu
nhi€n
lb
50cm
vd
c6 d0
cring k
=
100N/m,

v8t
treo o
<idu du6i
cfra
ld
xo
c6
kh6i
luong
m
=ZAO1.
Gin
ddu
rr6n
cria
ld xo
vio trdn
cfia mOt
thang mdy
vd
cho thang
m6y.chuydn.d6ng
chAm
ddn
dd; di
^uOogit
*
pnuoog thing
dr3ng
vdi

gia
tdc
2mls2.
LE
g
=
10m/s2.
Khi
vat
can
b5.ng,
chidu
dhi
cira ld
xo bdng
A.
47,6 cm
B.
48
cm
C.
52
cm
D'
52,4
cm
Cdu 10.
Chon
cAu dring
vd

s6ng
co hoc.
S6ng
ngang
vA s6ng
dqc.
c6
dac didm
chungld
A.
truydn
duoc trong
chan khOng.
R.
truydn
dugc
trong
chdt ran'
C.
truydn
dudc
trong
chdt
l6ng.
D.
truydn
dudc
trong
chdt khi.
CAu lL.

Cho m6t
mach
dao
d6ng
diQn
til
gdm mot
tu
di€n
c6
'diOn
dung
C
=
0,2pF
vI mOt
cuOn
thudn
cAm
c6
dQ
rd cim L
=
2mtlvd
di€n
tra
thudn R
=
0,1f).
Dd

cluy
tri
dao
dQng
didu hob
trong mach
v6i
hi€u
dien
thd
cuc
dai
ticn
tu
di6n th 4V
thi
phii cung cap
cho mach
m6t
cdng
sudt
bing
"A.
O,A.rO"Vl
'-_
"
n.
i,e.to;w
c.3,2.L0-4W
D'

6'4'104T/
a
t ,r z-'()fi
\'<-t
I
d^,-ct^n
CAu.12.
MQt mriy
phdt
di€n xoay
ohidu
m6J
pha
thf
nhdt,
phdn
cdm
c5 p
c4p cuc vi
16ro
quay
vdi
tdc d6
n vdng/s
thi
tdn
sd
cfia
sudt
di€n

dQng do
mdy
phrit
ra li
f. MOt mdy thrt
hai c6
3p cap
cuc
phdt
ra
ten
set
bing
4f
thi
r6to cria
,
n6
phii
quay
vdi
i6c
d0
ldn hon
may nt nfret
CAU
13.
MOt s6ng
co
truydn theo

m6t
phuong
truydn
s6ng
tt
M
ddn
N v6i tdc
ttQ
15m/s.
Phuong trinh
s6ng tai
M
veNHn-tqOtli:u"=acos(olt-n/3)mmviun=acos(ott-nll)mm.Khoangc6chMN=5cm.Tdnsds6ngbang
A. 10
Hz
B.25Hz
C. 50
Hz
D.
LZ5Hz
cau
14.
Didu
nio sau day
ld sai
khi
n6i
vd
dao

d6ng
didu
hoi cria m6t chat
didm?
4.
Van
tdc vi
gia
tdc
cta dao
d6ng
bidn thi€n theo,qui
ludt dang
sin
hoic cosin theo
thdi
gian.
B.
Hudng
cira vectd gia
tOc phu
thuQc vlo
vi€c chgn chi€u
ducrng
cta truc
Ox.
C.
Khi
di tlr
vi

trf
bi€n dcn vi
rri
cAn bing,
vAr
chuydn d6ng
nhanh
ddn .
D.
Khi
di tt
v.i
tri
cin bang
ddn vi
tri bi6n,
gratdc
c6 d0
l6n
tang
ddn.
CAU 15.
M4ch dao d6ng
c6 tg
C
=
8000 pF vi cuQn cim
L
=
lmH, di€.n trdkh6ng

ddag
kd
.
Hieu di€n thdcuc
dai
&
hai ddu
tu
li
1,5 V. Khi
hi€u
di6n
thd
cria
tu
diQn li 0,5V tbi cudng
dQ
ddng dien
qua
mqch bing
A.2.10tA
8.0,4A
C.zmA
D-4
mA
CAu
16.
Chon
d6p 6n
sai vd s6ng

am.:
A.
DO
cao cria em
khdngti
lQ
vdi
tdn
s6'am.
B.
D0
to cfra dm
khdng ti
l0
vdi
cudng
dQ am.
C.
Dd to cfia
dm
kh6ng
phu
thu6c vlo
tdn sO am.
D.
A;
sic c6li€n quai
m1t tniet vdi
dd
thi

dao d6ng
Am.
CAU
17.
Mdt con
lic lb xo
dao
d6ng
didu
hoi
vdi
bi6n d0
li 6cm
vi
pha
ban ddu
ldn/3.
Qu6ng
dudng vfr
di duo.c
trong
1/3 chu
ki,
kd tt rhdi
didm
ban ddu
li
A.
8 cm
B.

9
cm
C.
8,15 cm
D.9,26 cm
CAu
18.
Trong dao dQng
didu
hoi cfia con
lic
dcrn, d4r
lugnrg
nio
sau day phg
thuQc
vio
khdi
luqng cfia vat?
A. Lrlc
k6o
vd.
B.
Gia rdc cria
vAr.
C. Tdn
sd
g6c.
D.
Bi€n d6.

CAu
19.
d,rtrng
6nh sdng
ving, chidt
sudt tuy€t ddi c&a
nudc
li
4/3,
clndtsudt
ti ddi cfia
kim cucrng
ddi
v6i
nudc li
1,8.
Tdc
d0
c&adnh
s6ng
trong chAn
khdng li c
=
3.108m/s.
Jdc
tlQ cria
6nh
sdng vang
& trcn
trong

kim
cuorg
li:
A.2,22'108m/s-B.1,56.108m/s-c.2,84.10tm/sD.f2s'tb'd'
CAU
20.
Chon
d6p dn
sai
khi n6i v€'mdy phrdt
di€n xoay chidu
m6t
pha:
A.
Phdn tao
ra tt
trudng
gpi
ln
phdn
c6.m.
B.
Phdn
t4o
ra sudt di6n
dOng
xoay chidu
goi
li
phdn

r1ng.
C.
Phdn
cim vi phdn
rlng c6 thd
lh stato hoic r6to.
D.
Tdc
dd
g6c
cta
dbng
di0n bing
tdc d6
g6c
cria
rOto.
Cdu
21.
Trong
m4ch dao
dQng LC, tu di€n
dugc tich di€n
ddn di6n tich
cryc tl4r
ld
6 nC rdi
ph6ng
diQn
qua

cuQn cim.
Thdi
gian
dd
tu
ph6ng
h& In luo.
ng di€n tich tr€n
li
2
ps.
Cuirng
dQ
cgc
dai
cfta dbng
di6n chay qua
cu6n dny
biing
A.
1,59
mA
B. 3,14
mA C.6,28
mA
D.
12,56 mA
C,ilu22.
Chon
ddp 6n

difug
vd giao
thoa
s6ng
co vdi
hai
ngudn s6ng
kdt hqrp, cDng
pha
A.
Nh&ng
didm tr€n vln
cuc dai
dao ddng cirng
pha
vdi
hai ngudn.
B.
Nhdng
didm trOn van
cu.
c
tidu
dao dOng nguoc
pha
vdi
hai ngudn.
C.
Nhfrng didm
trOn vdn cuc

tidu c6
bi€n
d0 bing 0.
D.
NhEng
didm tren
vAn cgc dai dao
d6ng
v6i
bi€n
d0 cuc dai.
CAU
23.
MOt d6ng
co di€n
xoay chidu c6
diOn
trd
day
quAn
li
40Q,
khi
mic
vlo
mach c6
di€n
6p
hidu dung lh
200V

thi
sin
ra cdng
sudt co
hgc la 75W.
Bidt hq
sd c6ng
sudt ctra d6ng
co
le 0,85.
Cudng d0
hiOu
dung c&a ddng
diOn
chay
qua
d6ng co
bing
A.0,254
B, O,4A
C. O,5A
D.0,754
Cku24.
Hai khe
Yang c6ch
nhau 2mm,
mln 6nh
c6ch
mat
phing

chrla
hai
khe 2m. Chieu
s6ng
hai
khe
bing mdt
ngudn
sdng ph6t
ra ddng
thdi
hai bfc xa
c6
budc s6ng,t,
=
0,56
pm
vi
1z
=
0,64
pm.
Bd rong
.vlng
giao
thoa tr€n
min
id
L
=

2cm.
Sd
vdn
si{ng trtng
nhau cria
hai
brlc
xa
tr€n
li
A 5
8.6
c.7
CAU
25.
Mudn tdng
tdn
sd
ri€ng
cria
mach LC l€n 4ldn thi:
A. GiE
nguy€n
dd
u
cem
L,
giim
di6n
dung C

di
4 ldn.
B. Gifr
nguydn di€n
dung C
,
giAm
dO tu
ci.m
L di 4
ldn.
C.
Giem
d9 trl
cAm L dizldn vi
gi6m
diOn dung
C
di
I
ldn.
D.
Teng
dQ trl cim
L l€n 2 ldn
vi
tdng di6n dung
C l€n 8 ldn.
na
Cfim 26.

MOt
con
l6c lb xo treo
thing drlng,
dua vAt ddn
vi tri ld xo khdng bien
dang rdi
budng nhe,
vAt dao
ddng
didu
hod. Khi
vAt
di
qua
vi
tri cAn bang
thi vat
c6 vdn
tdc
20n
cmls.Ltiy
g=
10 m/sz;
nz
=
10. Chu ki
vd
bi€n
dd

i)
oao
oong oang
A.
0,4svh4cm
B.0,5svh5cm
C.0,8svi8cm
C.3cm
D.4cm
D. 1svdl0cm
C,dur 27.Trong so ctd
khdi
crla
mdt
mdy
phdt
s6ng
vd tuydn don
giin
khdng c5 b6
phAn
nlo
dudi
dAy?
A. Mach
phdt
s6ng di€n
til
cao
tdn.

B.
Mach
khudch dai.
C.
Mach
tdch s6ng.
D.
M+ch
bidn diQu.
CAu 28. Ddu
A cfra diy
AB
gin
vdi
mdt
Am
thoa dao d6ng
vdi
bi6n dd
ld
a, ddu
B
cd dinh,
tr€n dAy c6 s5ng
dtng. S6ng
tr6n dAy c6
bu6c s6ng 12cm,
khoAng
cdch ngin
nhdt

gifra
hai
didm
trdn
ddy
c6 cing bi€n dd
lh
a
vi
dao ddng cirng
pha
bdng
A. 1
cm 8.2
cm
CAu 29. Cho mQt
doan
m4ch AB
gdm
hai
doan
rnach ndi
tidp:
doan mach
AM
c6 di0n
tr& R ndi
tidp
v6i
mdt

tq dign,
doan mach MB ld mot cuon
cAm thudn.
DAt
veo hai
ddu doan
mach
AB
m6t
diOn
rip
xoay
chidu
v
=
30
Ji
cos
100nt(V); biet he sd
cdng sud't
cfra
doan mach AM
le
cos{p
=
0,6; di€n
r{p hiQu
dung
hai ddu do4n mach
AM

bang 4l5ldndien 6p hi6u dung hai
ddu
doan mach MB.
C6ng
sudt ti€u thu
di€n cfia
cA mach
bdng 48W. Di€n
trO
R bang
A. 12() B.
16Cl
c. 18CI
CAu 30. Bi€n
dd cira
dao ddng cudng
bric kh6ng
phu
thuOc
vio:
D.24
0
A. Bidn
dO cria
ngoai luc.
B. Tdn
sd cira ngoai lu.
c.
C.
Pha

cria
ngoai lrrc.
D.
Gdc thdi
gian.
C&u 3tr. Mach
vho cfra
mOt m6y
thu
radio
li m6t
mach
dao
dQng
gdm
m6t
cudn
dAy vi m6t
tu
di€n bidn ddi. DiQn
dung c&a tu diQn niy c6 thd
thay ddi tt Co
ddn 64C0.
Mach
dao d6ng niy
c6ng hu&ng
vdi budc
s6ng bang 100 m
rlng vdi di€n dung
cira

tu c6
gi6t4
16C0. Dii
budc s6ng mh
m6y
thu
duoc
li:
C?n32.
!d
xo
dd toa tiu tr€n c6c br{nh xe
dao dQng
vdi
phuong trinh
x
=
Asin2,5rut.
Chidu
d}i m6i
thanh
ray
ld
l= 12mvi
gifia
2
thanh c6
khe h&. VAn
tdc
thu bang

bao nhi€u
thi toa bi x6c m4nh nhdt?
A.54kmlh 8.45 km/h
C.
36 km/h
D.
30 km/h
CAu
33. Didu nlLo
sau ddy
ll kh6ng
chinh xric, khi
n6i
vd
tia
hdng ngoai?
A. Tia hdng ngoai
c5
bin
chdt
ld
s6ng
di€n tt.
B. Chi c6
cdc vat c5
nhiOt dQ
thdp
hou
5000C
mdi

ph6t
ra
tia
hdng
ngoai.
C.
Tia hdng ngoai
duo. c dtng dd sdy ho4c
su&i.
D. Tia hdng ngoai c6 tilc dung 10n loai
kfnh
inh
chup
Anh ban ddm.
CAu
34. Hai
didm
M
vi
N nam 6
cing mOt
phia cria ngudn
2m, tr€n cdng
mOt
phuong truydn
6m c6ch nhau m0t
khoing bing a, c6 mric cudng dd 6m le LM-
30dB
vd
[+r= 10d8.

Ndu ngudn
am dAt &
c]idn M
thi
mrlc
ctrdng d0
Am & didm
N
bang bao nhi€u?
Bidt
ngudn
am ln ding
hudng.
A.9dE
8.7
dB
c. 12
dB
D.t1dB
Cau
35. Dat mot
dien dp xoay chidu
vi.o
hai
ddu
doan mach
ndi tidp
gdm
mOt bidn
tr6. R, i:r6t

cu6n cdm thudn
vlr
mor tu dien.
Khi
bidn
tr&
R c6
gi6
tri
Ro
thi cdng
sudt ti€u
thu
dien cira doan
mach
ld ldn
rdiai.t
v). bang 100W. FI6i
khi
thay ddi
gi6
tri
cria
bidn tr3 ddn
gi6
tri zRo
thi cdng
sudt
tiOu
thu

di€n cfra doan
mach bang
bao nhi0u?
A.40W
8.50W
c.80w D. i20w
CAre
36.
I{hi
tia s6ng dcrn s6c di
qua
mdt
phdn c6ch
gifia
hai
mOi
trudng trong sudt khdc nhau,
kdr luAr.
nho
sau tIAy sai?
A. 20 m ddn 160 m
C.25 m ddn 200 m
2:.
A. ljudc song
tnay doi.
C.
Tdn
so
khong
thay ddi

8.20
m ddn 1280 m
D.25 m
ddn 1600 m
B. Miu
cria
tia sri.ng bidn ddi
D. Tdc
d,0 truydn
6nh s6ng thay ddi
C.0,48
pm
J
CAu 37.
Hai
con l6c don dao dong
didu
hod
6 ctng mOt
noi.
Tlong
cdng thdi
gian, con
lac
t\tt. nh2.t
tttrc irien drro-i;
8 dao dong, con l5c thf
hai
thuc
hi6n

duoc 10
dao
d0ng. Ndu
tdng
chidu dAi dAy treo cfra,
ccn lac7,
ddng thdi
giini
chi€u
dii dAy
treo
cfra
con
l6c
i
cilng mOt
doan 18cm
thi
chidu
dli dAy treo cfra chring
bang nhau. DA.li
tteo con
lic
I co ctueu dai la:
A.48 cm B. 64 cm
C.
84 cm D.
100cn'r
CAi-r 38,Trong
c6c.dung cu tiOu

thu
diOn
nhu
quat,
tir
lanh,
dOng
co,
ngudi ta
phAi
n0ng
cac he so
coag suat
nharc
A.
giAm
cdng sudi
ti€u
thu.
B.
tdng cong sudt toa
nhiet.
C.
ting cudng dd ddng diOn.
D.
giem
cudng d0
dbng
diOn.
CAu 39.

Hai khe YAng
c6ch
nhau
lmm,
miLn
6nh
c6ch
mdt
phing
chrla hai khe 2m.
Chidu sr6.ng
hai khe
bang mOt
ngudl
sdng
ph6t
ra
6nh
s6ng
don s5c
c6 bu6c s6ng,1.
Quan
sdt ving
giao
ihoa tr€n mln
thdy
6 r,An
giao
thoa
kd

t-idp
cdch
nhau 3,Bmm. Budc s6ng,t
bing
A.0,76pn-i 8.0,54
pm
D.0,38
pn-r
CAu
40.
Chon
d6p
6n
sai?
I
l.Sog
Am
truydn
til khdng
khi vio
trong
nudc
thi
budc
s6ng ting.
l. Fog
dnh
si{ng
truydn
rt

kh6ng
khi
vio
trong
nu6c
thi
budc s6n g giam.
9. Eng
6nh
s6ng
v1
s6ng
am
truydn
til
kh6ng
khi
vio
trong
nudc
ttti
tan
sd s6ng
khong ddi.
^
?-SEg
r{nh
s6ng
vir
s6ng

am truydn
trong
nudc
thi tdc
dg iruydn
s6ng
kh6ng
pfru
tn*O:"
tdn sd
s6ng.
-C_e*
41
lrcng
thf
nghi€m
vd giao
thoa s6ng
tr€n
miit
nudc c6iai
ogridn
tgihqp
A,B cirng pha.
fai
hai
didm
M
vi
N

0 cing
mQt b€n
ddi
vdi
dulng
trung
truc
cfia
AB vd
6 trcn*hai
van giao
thoa
cilng
loai;
til
M
ddn
N
cdn
c6
3 vfln
cuc
dai
khdc.
Cho
bidt
MA
-
MB
=

15cm vi
NA
-
NB
=
33cm.
Budc
sdng l, vi
tr4ng
rhdi dao
ddng
tai
M
vi
N
li:
A. 8cm;
vAn
cuc
dai
B. 6cm; vin
cuc
tidu
9 9*;
vin
crgc
dai
D.
gcm;
vAn

cuc
tidu
!.f,u fZ,
ttl-ot
do4n
mSch
gdm
mQt
hQp
kin c6 2
phdn
trl
(trong
sd 3
phdn
tt
R, L vi
C)
m6c
noi tidp vfi
mQt tu
di€n.
eiet
liar
69
loay
chidu
hai ddu
doan
mach

l€ch
p,hd
900
so vdi
di€n
ip
hai
ddu tu di6n.
Trong h6.p
kin c6
A-RvlC
I
B, L viC,
vdi
cim
khdng
bing
dung
kh6ng
C.
R. vd
L,
vdi
R bing t6ng
tr6 crja
doan
mach
D.
R vi
L,vdi

R bdt
ki
CAu
43.
MQt con
lic
ld xo dat
thing
drlng, vAt
treo
& ddu dudi cfia
ld
xo dao
d6ng
didp
hoi
vdi
chu
kt bing
0,5s.
nhidu
dii
tu
nhi€n
cira
ld xo
li
60cm,
chi€u
dii

lon nhdt cria
lb
xo
khi
vat
dao
igng
le
1ocm.
it
u=-i6*lrt;
n2
=
l0- Lfc vit
dang
&
dudi
vi
tri
cin
bang vi
c6 vAn
t6c
(L2n)cm/s
thi
chidu
dii ciralO
xo n
4.67,25
cm

B.
68 cm
C. 68,5
cm
D.69.,25
cm
Cau
44
Mdt
doan
m4ch
gdm
mot dicn
tr&
R
mic ndi tidp vdi
mot
cuon
cim
thudn.
H0 sd c6ng
suat
cria doan
mach
bang
l/3.Ti
sd
gita
cim
khdng

vi
di€n tr&
bing:
A.
J'
B.2J'
C.
JJ D.2J'
Ceu
45.
Chgn
ddq
6n
dring
vd dao
dQng
dt ddn vdi
luc
cin
khdng adittrcdung
vio
vit.
A' Vdi
con
l6c don,
ndu
tang
khdi
luong
cfra

vit
thi dao
dQng t6.t
ddn
nnaon
non.
B. Vdi
con
lic
lb
xo, ndu
ting
khdi
luqtng
cira
vdt
thi
dao dgng
tit
ddn
chim
hcnr.
C. V6i
con
l6c don,
ndu
kich
thich
vdi
bi€n d0 cing

ldn thi dio
ttEng
tit ddn
cing
nhanh.
D.
Vdi
con
lic lb
xo, ndu
kich
thich v6i
bi€n
do
cnng
ldn thi aao
Agig
tat ddn
cnig
ch4m.
Cdu 46.lvlQt
s6ng
dtng
tr€n
dAy
c6 dang:
u
=
2cos(bx +
nl})cos(lOOrct

- n\)(cm).Trong
d6 u
la
t
dO tai
thli
dl9q
,:*"
mQt
phdn
trl
M tr6n day
mi viiri can
bing
cria
n6. cr{ch
gdc
o
*Oi
rutoaog
x(x io
bdng m, t do
bang
giay).
Tdc
d6 truydn
s6ng
doc
theo
ddy

bang
g&n/s,
[e sd
U Uing
-
A.5n/4(m't)
B.3x/4(m-L)
C nl7(m4)
D.rl4(m4)
CAU
47.
MOt con
l6c
lb xo d+t
nam
ngang, vat
c6
khdi luo.
ng m
=
100
g,
lb xo c6
d9
cnlng
k
=
50
N/m. Dua vit
ddn

vi.tri
li
1o
n63
12 cm
rdi bu6ng
nhe,
vat
dao
ddng
tit ddn.
He
;d
ma s6r
gifa
vat vi
mir
ngang le
0,02.
Ldy
g=
10
m/sz, qu6ng
duong
ml
vft
di duoc cho
ddn
tini atog
lai b'ang

A. lZm'"
B.i8m
C.20m
D.Z4m
CAU
48.
Didu
ndo
sau
ddy
lh
sai
khi n6i vd doan
mach
xoay chidu
chi
c6 cu6n
cAm
thudn?
A. Cim
khdng
ti
lc thuan vdi
di€n
6p
hieu dung
hai ddu cu6n
cim vi
ti
lc nghich

v6i
gi6tr!
hiQu dung
cria
ddng
di€n
qua
n6.
!
Ddng
diOn qua
cu6n
cim
tr6 phanl}
so v6i di€n
6p
hai ddu
cuon
cAm.
C.
DQ
tf cAm
ciLng
ldn thi
cim
kh6ng cing
ldn.
D.
Chu
ki dbng

di6n
clng
l6n thi c&m
khr{ng
chng
nh6
.
CAU
49.
Mdt
ngudn
s6ng co
c6 phuong
trinh u^
=
2cos50nt(cm),
tdc
dO truydn
s6ng trong
moi trudng
li
7
'Smls.
Van
tdc
dao
dong cria
mQt
phdn
tr?

s6ng c6ch
ngudn O,Zm
tai thdi
didm
t
=
0,05s
li:
A. 0
B, Z5n
(cm/s)
C.
50n
(cm/s)
D. 5AJj
n
(cm/s)
Cau
50.
Dogn
m4ch xoay
chidu
ndi tiep
1
gdm
di€n
tr&
R; cuon thudn
cim
c6

d0
tu cAm
Lr; tu di€n c6
dion
dung
C-
"Qle
hu&ng
v6i
tdn
sd
f,
=
3oHz.
Doan
mach xoay chidu
ndi
tidp
2
g6m
dien tr&
R; cuon
ihudn cAm
c6 dQ ru
cirnln;
T {ie"
c6
di6n dung
C cOng
hu6ng

vdi
tdn
rd f,
=
40H2.
Ndu
ghZp
ndi
tidp
hai do4n
m4ch rr6n rhi
n6
cong
hrr6ng
v6i
tdn
sd
bdng
4.24
Hz
8.2+J2Hz
C.25Hz
o.
zs
Ji
Hz
Gi6m
thi coi thi
kh6ng
gi6i

thich
gi
th€m
'4
-
,r1::-::
i-: ii.::i
:. .illi
."
i
-
_.
1
:
::__.:::
i
j
I.i;i::.:::::!
i
1
j
l.
i_'1
:i
;-_":
i".j:
:
j_1.,;
i-l
:ij

.
.
',
:1 j'.,
: j _.a::-l,j::r4._.,r-
]
".1
:-i,r.r;;i,L:rj :.:1
z
TRLTGNG
TI.I|"T DAO
DUY TU
E{{I{yNG naru
CrAg
pg
rrw
rntr
s.ax E{sc
LAN
II
-
zsns
-
MOru
Var
r,v'
Cfru
1.
Dilng c6ng
thric tinh bi€n d0: At

=
A,3
*
Oi
*
2A1A2cos(gz
- g,); thay sd
ta
duoc
A
=
4rE
cm-
Dirng
cong
thric tinh pha ban
dAu
tang
=
(A,sing, +
Arsin<pr)/(A'cosg,
+ A,cosg,)
=
0-)
I
=
0;
n.V€
giin dd
vectcr

ta
thay
g
=
n.
V4Y chon C.
CAu
?.
Sring
si€u
dm c6
tdn
sd f >
20kHz,
n€n Itfu
hon 2kHz-
-+
Chon
D.
CAu
3.
Vi
tri
van
s6ng x
=
k).D/a
-+
l.
=

xaAD.
Thay
sd ta
duo.c l"
=
5ik(pm).
theo
bli ra 0,38(pm)
<
l"
<
0,76
(pm) +0,38(pm)s5&<0,76(pm) -+510,76<k<
5/0,38-+6,5<k<
13,2-+
c61
gi|tricirakthoimfrn->
c6 7
bric
xa cho
vhn
sdng trtng nhau
tai d6.
CAu
4. Ta
c6
Uo
=
.6Ur+
Up< Uo

-+
Chon
D.
CAu
5. Buoc s6ng
cia
s6ng
Am trong khong
khi
li
)"
-
vlf
=
340/136U
=
0,25(m).
Khi
c6 song
cirrrig
trong ong
thi
chidudii
ceitkhongkhitrongdngbengl=(2k+1)X/4-(2k+l)0,2514(m)=6,25(2k+l)(cm).Tac60<l<
60cm-+
O<6,25(2k+ l)
<
60
(vdi
kngny€n

duong)-)
0
<k<
4,3
-+
VAy
c6 5
gi6tricfia k
thoimdn
->
c65
ldn
nghe dm
li
to nh{t
-+
Chon B.
Cau
6.I{aidao
d6ng
nguo.c
pha nhau
thi bi€n
do
cfia
hai
ciao
dOng c6
thd
ln

bat k)
gid
tri
nho,
khdng
nhat
thiel
phii
bang nhau + Chon
B.
CAu 7. Theo
c6ng thrlc U1/J2
=
NrA{:
-+
100/60
=
12004'{:+
N:
=
720
vdng.
->
dicn rip hiOu
dung tr€n m6i
vdng lh
IJ
=
6Afl20(V)
=

1/12(V). Coi
so
vdng
qudn ngud.c
li n, theo bii ra
ta c6
(720
-
n).(lll2)
-
nll2=
40(V)
-+
n
=
120(vbng)
-+
Chon C.
CAu B.
Theo SGK
Vat
ff fop li thi mdi
vach nidu
tr€n
kinh
Anh trong budng
6nh
cfia
nii{y
quang

phd la
Anh don
sjic
cira
khe F cira 6ng
chudn truc
-+
Chon
C.
Cdu
9.
Khi
con lac chuydn dOng di xuong
chirn
ddn
ddu
thl
xudng dudi
,
ktri d<l
vAt
chiLr tdc
dung cria 3 luc:
luc
quzin tinh
luc
quiin tfnii
tr{c
ch-rng
vlo vai

huing
thing
dring
{,
ui
ttvn8
lqc F
}rLrdng
rhing
dring xuong
drt6i,
luc
din
l1,5i
f,,,
hu6ng
thing dfrng l€n
tr€n
-+ Khi
vAt cAn bang
Fon
=
P
+
lin'
-)
k'A!
=
rng
+

n]a
->
z\1= m(g
-t-a)/ft
=
0,2i10
-r-2)1100
=0,024m=2.,4cm
-+
chidu
diicita
lb xo
bang 1=
lo + 4l
=
50 *2,4
=
52,4cm
-+'Chon
D
(-lAu
1{}.
S<ing cloc tlrvrirr
ducr.c
tlong
c6c m,ii
trubne rin.
l6ntr.
khi.
cbn s5ng ngang

irui'$n
ducrc
trong
clra[rin
-+
s6ng
ngang
v"i
s<5ng cloc cidu truydn
cluoc
trong
chat ran
-+
Chon
B
CAu 1i.
COnj
sr,at
cdn
cung cap
cho
mach
chlng bang
phdn
cOng suAl
mat miit
tlo
toA
nhi€t.
Ta

c6 LI6?
=
CUo:-+
Iot
=
CUut
fi =
0,2.tO6.qtl1.t0";
=
0,0016-
Cong
suit mdt
mdt
do
toi
nhi€t P
=
ItR=
(lorl2)R
=
0,0016.0,1
=
0,E.104w
-+
Chon C
Cf;u
J2. Tdrr
s0 cira strat c1i0n
d6ng do mdy
thrl nhAt

phdt ra
f
=
np,
tdn so
c&a
sudt
diOn
d6ng
do mdy
thf
hai
phlrt ra lh
4f
=
3pn'-+
4np
=
lp1l'*
n'
=
4nl3-+
t6'c dO
clLray
cira ntriy
thfr hai lon hon
mriy
thfr
nhAt
li n'-

n
=
n/3
->
Chon C
CAu13.DOl€chphagiualr,{viNi}Ag=2ttdl}".Tac6Arp=-xl3-(-xl2)=nl6,thr-ryd=5ctl +}-=60cm->
tdn s0 s6ng
f
=
vll,=
1510,6
=25llz
+
Chon
B
Cnu 14. ftu'Otlg
ciia
vecro
gia tdc
luon hu6ng
vd
vi tri
can baug nrI
khOng
phLr tlrr-rOc vho
vi€c
chon
chidu duong
cfta truc toa
dd + Chon B

CAu 15.
Ta
cr5
LIur
=
CUo?-+ Int
=
CUo'/L
=
8tJ00.10-rr.1,51li0'r
=
1.8.10i. Ta
lai
cri
(Lr/Uct) +
(i/int)
=
1. Thay
Lr
=
0,5V,Uo
=
[,5V
vilot
=
1,8.10'5taduo.c
i=
4.10-3A
=4mA
->

(}rott
D
Cau
16.
V6i
cirng
nrOt
crrinrg c16 am
rhl
khi
thal,cldi
tdn
so
thl
d0 to cira itn thall
ddi +
D-o
to
cira
Am
phu thuoc
vi.,-r
tdn
sd inr
+
Cirori
C
CArt
l7.liong
1/3

chu
ki, didm
chuydn
d0ng
trbn
ddu
quay
duo-c
rnot
g6c
cL
-
(ot
=
(ZnlTII'l3
=
2nl3
(tir
M
rien
N
tren
vdng
trbn)
-)
trcn
truc Ox
Vat
ditirlden
N-+

Qulngduhgdiduo.c
li s=OI
+ ON=
Al2+
A
=
9ctn
N
l'l
-+
Cllr,-:'l
B
CAu
18. I-r.tc
k6o v€
F
=
- mgx/l
-z
ndn
n5
phLr
thuOc
vio
k[,Oi
lrtr:ng -+
Chon
A
iF':lr'.r
:€ii ::r

":,:
r :' :r.'
+rr.::,ri:qr.;l
r,;
.r
.t:,::;i

il,
3ii :t
.:
r
a
j
:r:
.i1,
-:i-, _ :;.;_t]-t{i,*"
'
,.
.l*
,
,
,r- .:
ji!:r;.
,-,o,*,"-ri*;', o.:;.,-,r-i*
:
.,_
: 1r
I'
j
-;r:r:.i.,i.r;:.1.i:-:::t-

,st
u
l*-t
Cnu 19. Chidt suit
tuyet doi
cria
kim
cudng li n2,
cria
nudc
li nr thi chiet suat ti d6i
cria
kim
cuong d6i vdi
nu6c
li nr,
-
nrln,-> n2
=
nirnr
=
1,8.4/3
=
2,4.
Chiel sudt tuy6t doi
cfia
kim
cuong
ld n"
=

c/v
-+
toc
dQ
rinh
siing
trong
kim
cucrng
lh
v
=
c/nr
=3JOBI,

=
1,25.1d+
Chon D

CAu 28.T6c
d6
g5c
c&a dbng di€n
o
-
LTf
,
cdn tdc d6
quay
cfia rdto li or'

=
Zrn
=Zttf/p
(
v6i
n lI sd
vdng
quay
"-e:rcir2
1g1o trong
ls,
p
li so
cap cuc tU cira
mdy) +
G) * c0'-)
Chon
D.
,.,;.*$eu
21.
fhdi
gian
dd tu ph6ng
hdt ll2luong
di€n t(ch cuc
dai ln
l/6
chu
ki
-+T/6

=
2ps
-+
T
=
12ps
=
12.1O6s
6*;;=;
tdn
so
g6c
cira clbng di€n trong rnach li a
=
Zn/T,
=
l06x/6
(rad/s)
+
giri tri cu. c dai cira
cubmg
d6 ddng
di€n
=#+;ffiu
rn4ch
li
Io
-
ogo
=

(106n/6).6.10-e
=
3,14.1or
(A)
=
3,l4mA
-+
Chgn
B.
;El::$eiiu
22. Nhrhg
didm tr€n
van
cgc tidu c6 thd
c6 bi€n
d0 khri.c 0 ndu bi€n dQ
dao
dQng hai ngudn
khdng
bang
nhau,
cdn c6c didm
trdn
vxn
cqc
dai thi
lu6n
dao d6ng
voi
bi€n

dO cuc dai
-+
Chgn
D.
Cau
23.Y6i
d6ng
co di€n thi cong suAt ti€u
thu di6n
cria d6ng
co
rD
=LlIcosrp
=
I2R
+
./)co
+ Thay
sd
vlo ta
ducrcphuongtrinh 8Ir-34I+ 15
=0-+
Phuorg
trinh c62nghi€nrI=0,5AvirI=
3,75A.
NghiQmi=
3,75Ab!
ioai
vi
khi

tiray v}o ia thdy
cong
su{t toA nhiet rdt
ldn so
vdi
c6ng
sudt cc hoc n€n
nghi€rn nby
kh6ng
phit
hqtp
+
I-dy I=
0,5A
-+
Chon C.
CAu24.Tac6k,l,,=kzL-+0,56kr
=0,64k2 +7kt=8kz-)kr=8-+khoingc6chgitahai
vitritringnhauk€
tiep c&a
hai
vAn
si{ng tr€n
bang
xo
=
krlrD/a
=
8.0,56.10''.2nJ0't
=

4,48(mm).
Bd
rQng
virng
giao thoa ren
men
lh L= Zcm,cdc
vi
tri trtrng nhau tr€n min li x
=
4,48k(rnm)
+
-W<x<Lfz
-+
-10<4,48k
<
l0
-+
-2,23<
k
<
2,23 +
c6 5
giri
tri ctra
k lh nguy€n
-+
c6 5
vi tri trirng nhau cia hai
vAn

s6ng
cila hai
bric xa
tr€n
-+
Chon
A.
CAu 25. Tdn
s6 cfra
mach
LC
le f
=
UQx^l
LC
)+
khi
giAm tich LC di 16 ldn
thl
tdn sd f tang
4 lAn
-+
Chgn
C.
CAu
26. Kh!
dua
vdt
ddn
vi

tri
ld xo
khong
bidn
dang rdi buOng nhe
thi bi€n
dO A bang
dQ bidn
dang
cta
lb xo
khivdtcAnbangAl-)v-*=o)A=
AG/N
=
{g*<-(0,2n)2=
l0A-+A=0,04(m)
=4cm-)0)=v /A=
20n/4
=
5n(rad/s)
+
Chu ki T
=
Zrla
=
0,4(s) +
Chgn A.
Cilu
27 .lvlach td.ch s6ng 6 mriy thu s6ng
vo

tuyen
-+
Chon
C.
-,,.
.
CAu 28.
Tir
c6ng thric bien do
s6ng dtmg
4
=
l2acos(2ndl\'
+
n?)l
=
a, v6i
d
lh
.::.
klioirng cdch tir di6m t(nh bien
dQ M
ddn
nrit
-+
Zacos(2nd/?'
+
N/2)
=
*a-+

C
cos(2ncll}" +
rcn)=
+ll2
->2ndhl-
nlT=2n/3
(Xnl3
khdng
chort
vl
d
<
0 +
d=)v/li=
f:ii:a.Z
nrlrt kd ti-ltp le
CD
=a12
=
6cm
-+
Khoing
c6ch
MN
=
4cm + Cnon D.
CAu 29. Ta
c6
giiin
dd

vecto
nhu
hinh
v6, trong
d6 UAM
-
4UJ5,
coso
=
singonn
=
0,8
Dinh li hdnt
cos
lJort
=
Uor,' + UL2
-
2UorUrcoscr
->
I
ur? +
l6uL1p5- 2.4u1u1.0,8
-
302uAp1
=
4.50/5
=
40(v)
-)

ur,
=
50(v)
Un
=
U^n, cosqAM
=
40.0,6

Z4(V). Tir
cOng
th'lc
rD
=
U*3/R
->
R
=
Un?
rJt=242148
=
l2(O)
-+
Chon A
Ctiu 30. Bi€n
do
cfia
dao clong
cudng
bfc

phu
thu6c
vho
bi€n
do
vti
tdn
so cria ngoai
luc
tfic
li
phti
thuOc viro pha
cuii dao d6ng
mi
kh6ng phu thudc
vio vi0c chon
goc thoi
gian
-+
Chon D.
Carr 31.
Budc s6ng
)"
=
c.2nJTC
. Theo
bdi ra
ra c6
".2"r[nOq

=
100(m)-+
a(
c.zn$C.,
)
=
l00m
->
^
r;;-
c.?n,JLL'o
-
25rn;
+
c.Zn

8(c.2n
$.C"
) =
8.25
=
200m.
Vay
dii budc s6ng mh
m6y
thu
cluo.c tit
25m
den 200m-+ Chon C.
(.nu

32- Toa
xe bi
x6c manlr nhit khi
c6
c6ng
hudng
co, khi
d6 chu
ki
dao dOlg
cria
ngoai
lu. c ti{c
dung
vdo
ld xo
l-ring
cliu
l<i
clao
d0ng
ri€ng cira
lb xo.
Chu ki
riing
cira
ld xo lh
I
=
2nl(2,5n\

=
0,8(s)
-+ vin toc
cira thu
v
=llt=
1210,8
=
15(m/s)
=
54kmlh-> Chon
A.
CArr
33.
'fdt
c|cic vat d€u phr{t
tia hdng
ngoai
->
C}ron B.
{-li.u3,$.GoikhoingcrichtirngudnAmddnMlhcl+ti
sdcuongcJ,SAnrtaiMviNleIM/I^,=10?=(d+a)?d2->
(cl+a)/d=10->a=9cl.Khid6
l*=rp/(4ndz1
=8lr12714za1.Khi
ngudndattai
MthicudngdoArntai
Nlh
'
:';':

rr:iiri:::l:1
'r'lr'-
:
'::'
::';t;
i
1:'
'rr,,=r/)/4na2)Ir,/Bl-+LM-Lu'=101g(Ir,[")=l01g8l*:19(dB)+L*'-LNi-19=30-i9=11(clB)+Chqn
D
CAu
35. Thay
ddi
bien
trdR
dd cong suar
tieu
thu
cli6n
clat
cuc
dai
th'i R6
=
lZ,
-Zrlvi'
c6ng
suAt
crc
dai bang
q),,,.=Utl(2RJ

=
1000il).
I(hiR
-
2Ro
thi
tdng
trb-t
=4Ro?+
Ro'=
5Rot
-+
I
=
rJlz=
ul(R."'6)+
Cong
sudt
tidu
thu
diOn
bangrp
=
I?(2Ro)
=
2Ro
U2(sRo)?=
2u75Ro)
=
80@) +

chon
c'
Cau
36.
Khi
di
tt m6iiro*gi.ong
suat nay
vao hoi
truinrg
rrong
suat
khdc
th} budc
s6ng
thay
ddi
nhung
tdn
s6
khdng
thay
ddi n6n
mhu
s6c
tia s6ng
don
sfc
khdng
thay ddi

->
Chon
B'
CAu
37. Trong
cing khoing
thbi
gian
lir
t, con t6c
iir*
nhat
thuc
hi€n
duoc 8
dao
dong
-+
citu ki
T,
=
t/8' con
lac
2
thu.
c
hi€n
duo.
c
l0

dao dong
-+
chu ki
T2
=
t/10
s T,ff,
=
J/4.
Chidu
ddi
cdc con
lac
ii
l,
vh
l,
th)
the':
b2Li
ra
1'

lgcm=l:*
lgcm-+lr-lz=36cm-+lr=1,-_36cm.
T{r2=
{Jh=514-+l,A'=25116-+
Iri(lr
-36)
=25/16

-)
11=
100(cm)
+
Chon
D.
Ciru
3tt.
C6ng suat
hao
phi trong
ciic
clung
cu
dicn
ld
cdng
sudt
toA nhiOt
(Orr=12r
=
{F/N2cottq)
-+
khi
tang
h€
so c6ng
sudt
cosg
rhi cutrng

d9 hieu
dung
cria
ddng
di€n
giim
-+ c6ng sudt hao
phi
gilm
->
Chon
D'
cdu 39.
6 van
giao thoa kdliep
cdch nhau
3,8mm
-+ 5if2=
3,8
->
khoing
van i
=
l,52mm.
Ta
c6 c6ng
thrlc
tinh
bu6c
s6ng 6nh sring

I
=
ia/D
=
1,52.1O'3-
10'3/2=
0,76(pm) -+
Chon A'
Cnu
40. iO.
a9
t*lyen s6ng
Am
trong nudc
lh
kh6ng
ddi khong
phu
thLr6c
vlo tdn
so s6ng,
cdn
s6ng
r{nh
sdng
c5
tdn so khr{c nhau
thi
t6c oJtruydn
sZng

Ih kh6c
nhau.
Li
do:
khi
di
tir
khong
khi
vro.trong
nu6c
thi
tdn-sd
rinh
ra"g tt'6;g
adi, .ttid,
sudr
cria nudc n
=
c/v,
rinh
sd.ng
c6
tdn sd
kh6c
nhau
thl
chiel
sudt
n

cria nu6c
lh kh6c
nhau
+ tdc
d0
truyiin
s6ng
v
li
khdc nhau.
VAy
D
sai
-+
Chon
D'
CAu4l.GilsfrMvlNdtiundmtrdnvAncu.cdai:MnamtrdnvAnthfkthlNnamtrdnvAnthfk+4-+MA-
MB
=
kl,
=
I5cm;
NA
-NB
=
(k
+ 4)tr
=
33cm
-+

(k
+4)/k
=33/15
+k
=
l0/3
4Z
-+ khdng
thoA
mdn.
V4y
M
v)
N
cing
ndnr
tren
van
cu.c tidu
-+
M
nam
trOn
vdn thfr
k,
N
ndm
tr€n
vfln thrl k
+ 3 +

MA
-
MB
=
(2k +
l)hlT
=
iicm;
NA
-
NB
=
[2(k
-F
3) +
17?t12
=
33crn
->
6LE
=
lScm
->
].
=
6cm'
V4y M
vi
N
cr)ng

nam
tr€n
vin cuc ti,iu
vl buoc s6ng
l"
=
6cm
+
Chon
B.
Cau
12.
Didn
6p hai
dAu
doan
mach
l€ch
pha 900
so
v6i
di€n
6p hai
ddu
tu di€n
-+ dien
dp hai
ddu
doan
rnach

cilag
pha v6i cuirng d6 dbng
di€n +
nrqch
c6
cong
hu6ng -+
hQp
kin
phAi cd di€n
tr& thudn
vi cuOn
cAm thudn'
i hi
ti5 idng irtr Z=1i.
+
Chon C.
ija,*
43.
'1'a
cd T
=
0,5s
-+
trin sd
g6c
a
=
Znlat=
zln(ntd/s)

-+
clo
bi€n
ciang cira ld
xo
khi
vat
can
bang Al
=
glaz
=
l0l(4n)2
=
6,25(cm).Chidudnicuc
ciai
cila
ldxol-".
=
lo+AI+A
-+
70=60
+6,25
+ A
-+
A=
3,75cm'
Tri
,ong ifruc A.
=

xj
+
iui<ot.
+
3,:51=
xt
+
(l1nl4ril
i;ii
=
7,25cia,
'"'l
i'at c
Cufr'.'r
tli
ci-n
br.ng
n€n
khi
d{i
cliiOn ci2ri cua lo xo bdng
l= lo
+
Al+
lxl=
60
+ 6'25
+2'25
=
68'25cm

-+
chgn
c'
ciru
44.Tac6cosrp
=ll3
-_>R[z=
tl3_>RlF
+4
=113
-+(R:
+Zr2)/R==g
->
t
+ZJlR'1
=9->
ZrtlR'
=
8
-+
ZL|R=zJ| >Chon
B.
CAu
45. A.
Vdi
con
l6c
don, leu
rang
khoi

luong
th)
co ning
con
lic tang
(W
=
nrgH)
+
tat
ddn
chAm
horr
-+
A sai.
B.
V6i con
lac lb
xo, ndu
tang khoi
iuorrg
thi
co ning
con
l6c
kh6ng
ddi
-+
kh6ng
inh

huong
t5'i
dao
d0ng
+ B
sai.
C.
V6i
con
l6c
don,
ndu kich
thich
v6i bi€n
dO
cirng
lolr
thi
co
ndng
cort
litc
tdng
->
C
sai
D.
V6i con
lic lb xo, neu
kich

rhich
v6i bign
do
cdng
ldn
thi
co nf,ng
con lac
tang
-+ dao
dOng
tit
dAn
cirng
cham
+
D
dfrng
-+
Chon
D.
Cnrr
46.
Mot s6ng
dirng rr.en
diy
c6 dang:
u
=
Zcos(bx

"r
n/2
)cos(
100nt
-
nlT)(cn1->
I
=
vlf
=
80150
=
1,6rn/s, he
sd
b
=2n17.=2x17,6
=5x14
(tn-')
+
Chon A.
{)iut
4'/. Khi
vtir chir-r tiic
dLrng cua lr.rc
ma
sdr
th)
co
nang
bierr

ddi
tiriLrrh
c08g
cArt
cia
lrLc
ma
siit
-+
kA2l?
pmgs
->
quing
ciunng
s
=
kA'/(2FrnB)
=
50.0,
L22l(2.A,02-0,
l. l0)
=
i 8(nr) +
Chqn
B'
bau
as.
ianr [l,ang
ir,u
ttruo.'oio

t"ar, sd
f
ci,a
dbng
c1i€n
v)L
cld
tu cirn
cua
cuon
cim mii
khong
phu
thu6c
vho
cli€n
ip
hi€u
clrrng
hai
ddu
cuon
cftm
vi
cLr&ig
dO hi€u
dung
cla
dbng
diOn

qua no
+
A
sai
->
Chon
A
CAu
49.
phuong
trinh
s5ng
tai
didm
M
c6ch
ngudn
li
x
c6 dang
u",
=
2cos(50nt
-
Znx/L)
(cm)'
Vin tdc
dao
d6ng
cira

phdn
t& s6ng
M
lir
voo=
du/dt
=
-
100*sin(5ont
-2nx/7u)
(cm/s).
Budc
s6ng
X=vlf
='7,5f25
=0,3m;
thay
x
=
o,Zm
ve t
=
0,05s
ta
duoc
vaa
=
5On(cm/s)
+-chon
c'

-CAu
50. Ta
c6
t,
=
l/(Zx^[L,C
);
fz
=
tlQnr[I.C
).
Khi
ghdp
ndi
tidp
hai
doan
mach
v6i nhau
th\Zv=
'i;,*Zr,
-)
L
=
Lt
+ I-2,
<li€n
dung
cria
b6

tu
ll
Cu
=
CIZ-+
n6
cQng
huong
vdi
tdn
sd
f
=
"",j!(r"J(2,
*
L,)c
t2)-+
":
tlf
=
(41fL.C + 4nztnc)fz
=
(l/f
,2
+
2'+,!2
(FIz)
-+
Chon
B.

\ffhn=
o3o'z
+ 1140112
=
50'/(2-302.402)
-+
f
=
',12
'30'40/50
=
Me dd
201
Me dd
202
Me
dd 203
Ma
dd204
I
C
26
A
I
C
26
D
I
A
26

A
I
B
26
A
2 D
27
C
2
C
27
D
2
B
27
D
2
A
27
D
3 D
28
D
3 D
28 B
3
c
28
C
-

J D
28
D
4
D
29
A
4
D
29
C
4
C
29
C
4
C
29
A
R
-?0
D
5
A
30
A
5
D
30
D

5
D
30
D
6
B
3l
C
6
D
31
B
6
A
3l
C 6
B
3l
D
7
C
32
A
I
D
32
C
7 B
3L
B

7
A
32
c
8
C
33 B
8
A
33
C
8
A
33
C
8
C
33
D
9
D
34
D
9
C
34
B
9
C
34

B 9
C
34
A
10 B
35 C
10
A
35
D
10
B
35
D
10
A
35
C
1l A
36 B
ll
A
36
C
l1
A
36
A
1l
D

36
B
t2
C
37 D
12
C
37
B
l2
D
37
C
t2
C
3't
B
t3
B
38
D
t3
D
38
B
13
C
38
C I3
B

3B
C
1A
LA
D
39
/\
l4
D
39
IJ
l4
A
39
D
t4
B
39
iJ
15 D
40
D
15 B
,i0
D
IJ
(l
40
B
l5

A
4U
IJ
r6 C
4l
R
t6
D
4l
B t6
B
4t
D
r6
C
4l
B
l7
B
42
C
l7
B
42
B
11
lt
D
Ar)
C

l7
A
42
B
18 A
43
C
18
B
43
C
l8
D
43
D
l8 D
43
B
19
D
44
B
19
D
44
B
19
D
44
C

r9
D
44
D
20
D
45
D
20
A
45
A
20
B
45
B
?0
C
45
C
2l
B
46
A
2l
C
46
2l
B
46

A
2l
D
46
C
22 D
47
B
22
tl1
C
22
B
47
B
22 B
47
D
ZJ
C 4B
A
ZJ
C
48 D
23
D
AO
+o
D
D

23
D
Aa
TU
L
24
A
4\)
24
D
49
D
24
D
49
D
24
C
49
B
25
s0
B
25
B
s0
25
D
50
A

25
50
D
{