Vdy chgn dap an D... Cdu 33: M o t nguon diem O phat song am c6 cong suat khong doi trong mot moi trifdng truyen am dang hifdng va khong hap thu am.. Hai diem A, B each nguon am Ian Ix
Trang 1Cdu 31:
U m
at cha
t lon
g c
6 ha
i nguo
n son
g A , B each nhau
18 cm
, da
o
dong the
o phtrcfn
g thSn
g duTn g
vdi phMng
tr in
h l
a U
A = U
B = acosSOTit
iv6i t
ti nh bang s) To
e d
o truye
n son
g c
f m
at cha
t lon
g l
a 5
0 cm/s
Go
i
O l
a trun
g die
m eu
a AB , die
m M
or ma
t cha
t lon
g nk
m tre
n diTdn
g
trung trtf
c cu
a A
B v
a ga
n O n ha
t sa
o ch
o pha
n tu
f cha
t lon
g t
ai M
dao
dong cun
g ph
a v
di pha
n tu
f cha
t lon
g t
ai O Khoan
g eac
h M
O la
:
A 1
0 cm B 2
cm C 2
V2 cm , D
2V i0
cm
Giai
d
^
^
A
0
B
Phi/cfng tr in
h son
g t
ai mo
t die
m M tr en di/ofng trun
g triT
c v
a die
m
Ola : 27ld^ 507rt OS C 2a u^^ =
; U
Q = 2acos(507rt-97c)
27id TI = Acp^ =9 2k7i=>d
= 9 -2 k>
AO = 9^
k<
Ta
c6: dmi
n
k
hi v
a ch
i kh
i k
^ax =
-1 , su
y ra
dmin = 11
Kh
i d
o M
O = 7 dL -A 0^
= 2710
Vdy chgn dap an
D
Cdu 32:
M
ot s^
i da
y da
n ho
i can
g ngang , dan
g c
6 son
g diTn
g o
n dinh
Tr en day, A la mot die
m nut , B la mot die
m bun
g ga
n A nhat, C
la
tr un
g die
m cu
a A
B, v6i
A
B =
10 cm Bie
t khoan
g t hd
i gia
n ng^
n nha
t
giufa ha
i I an ma l
i d
o da
o don
g cu
a pha
n tu
f t
ai B bang bie
n d
o da
o
dong cu
a pha
n tu
f t
ai C la 0,2
s To
e d
o truye
n son
g t re
n da
y la
:
A 0 ,25m/s B
0 ,5m/s C
2 m/s D 1
m/s
Giai
Ta c6 bie
n d
o son
g dCfn
g t
ai mo
t die
m M tr en day, eac
h da
u c
o
dinh
A doa
n d la : 27id sm- 2a = AM
X vdi
a l
a bie
n d
o nguo
n song
12
0 Gilii ch
r t ig td
S th
i T
S BH
, C
D
Mo
n V$
t I
I
Trang 2- Bieii do song t a i diem B
- Bien do s6ng tai diem C
d„ = - = 10=>> = 40cm
" 4
dc =
= 2a.—= A,
AB I
2 ~ 8
Vi GO the coi diem B nhtf mot chat diem
dao dong dieu hoa vori bien do A B , t h i thdi
gian ngan nhat giOfa hai Ian diem B c6 l i do
\ r
_ Jt
T X 2
At = - = 0 , 2 ^ T = 0,8s=>v = - - 0 , 5 m / s
- 4 T
Vgy chon dap an B
Cdu 33: M o t nguon diem O phat song am c6 cong suat khong doi trong
mot moi trifdng truyen am dang hifdng va khong hap thu am Hai
diem A, B each nguon am Ian Ixiat la ri va r2 Biet ci^cfng do am tai A
gap 4 Ian ci/&ng do am tai B T i so — bang:
2
4 Giai
Ap dung cong thufc
Vdy chon dap an A
Cdu 34: Dat dien ap u = UV2 coscot vao hai dau mot tu dien t h i cUcfng
do dong dien qua no c6 gia t r i hieu dung la I Tai thoi diem t, dien ap
Trang 3ai da
u
t
u d
ie n
1^
u v
a cifcfn
g d
o don
g die n
qua
no l
a i
He
thijfc lie
n
he giiJa ca
c d
ai lu"crn
g l a:
2
-2 1 " >
-2
Giai
Vi u
c vuon
g ph
a i n en
giOfa chun
g luo n
c6
mot cong thuTc do
c la
p
2
-2
thcfi gian :
——
+ —
=
1
Suy ra :
^3
—y
+
—
—
^ =
1 =
> — + = 2
Vdy chgn dap an
D
Cdu 35:
M
ot ho
c sin
h qua
n mo
t ma
y bie
n a
p v6i
dii din
h s
o von
g da
y
cua cuo
n so
r ca
p ga
p ha
i Ia
n s
o von
g da
y cii
a cuo
n thu
f cap D
o sc
f sua
t
nen cuon
thuT
cap b
i thie
u m
ot s
o voii
g day Muo
n xa
c din
h s
o von
g j
day thie
u d
e qua
n tie
p t he
m va
o cuo
n thu
f ca
p ch
o du , ho
c sin
h na
y da
t \
vao ha
i da
u cuo
n sc
f ca
p m
ot die
n a
p xoa
y chie
u c
6 gi
a t
ri hie
u dun
g
khong doi, ro
i dun
g vo
n k
e xa
c din
h t
i s
o die
n a
p d cuon thtr ca
p d
e ho
f
va cuo
n sc
f cap Lii
c da
u t
i s
o die
n a
p bkn
g 0,43 Sa
u k
hi qua
n the
m
vao cuo
n thu
f ca
p 2
4 von
g da
y t
hi ti
so die
n a
p ban
g 0,45 B
o qu
a mo
i
hao ph
i t ro ng m ay bien
ap D
e disac
may bien ap diing nhi
f di
T
dinh,
hoc sin
h na
y pha
i tie
p tu
c qua
n t he
m va
o cuo
n thu
f cap :
A 10
0 von
g day B 8
4 von
g day
C 6
0 von
g day D 4
0 von
g day
Gihi
Goi Ni , N 2
a s
o von
g da
y ba
n da
u cu
a m5
i cuon
; n
l a
so von
g da
y
phai cuo
n t he
m
N N +
0,45 N , =
1200;
N, =
^'
=2
^n = 60
Vdy chgn dap an
C
122 GiaJchitietdethiTSDH,CDM6nVatl
i