DE THI TUYEN SINH CAO DANG NAM 2010 M6n: VAT LI - Khoi A Thdl gian lam bai: 90 phut Cho biet: H S n g so Plang h = 6,625.10"^'*J.s, toe a n n sang chan k h o n g c = 3.10^m/s, Idn dien t i c h nguyen to e = 1,6.10"^^C, so Avogadro N A = 6,02.102^mor\V = 1,6.10~^^J Cdu 1: Cho p h a n uTng h a t n h a n | H + | H ^ ^,He+Qn + 17,6MeV Nang li/cfng toa r a k h i t o n g hgrp duo'c g k h i heU xap x i bang: A 5,03.10" J B 4,24.10^ J C 4,24.10^ J D 4,24.10" J Gial N M o t m o l He c6 4g nen so nguyen tijf t r o n g I g He l a : N = —— Nang \Mang toa r a : E = N.17,6MeV = , ' ^ - 17,6.10^1,6.10"'^ = 42,38.10'° « 4,24.10" J Vay chgn dap an D Cdu 2: M o t m a c h dao dong dien tCf LC l i tiidng dang thiic h i e n dao dong d i e n tii t U D i e n t i c h ciTc d a i t r e n m o t ban t u la 2.10'^C, ciro'ng dong d i e n ciTc d a i t r o n g mach la 0,1 TTA Chu k i dao dong dien tif tif t r o n g m a c h b k n g : A 10'^ s B 10"^ s ^ C 4.10-'s D 4.10-'s Glai N a n g li/grng m a c h dao dong: 2 1- Chu k i dao dong: T = 27r>/LC = ? : ^ = ^^"^"^^ 0,l;r = 4.10'(s) Vay chgn dap an D Cdu 3: T a i m o t v i t r i t r o n g m o i trifdng t r u y e n a m , k h i cirdng am tang gap 10 Ian gia t r i ciXdng a m ban dau t h i mu'c cu'dng a m D g i a m di 10 d B C t a n g t h e m 10 dB B g i a m d i 10 B A t a n g t h e m 10 B 84 G i a i Chi ti6t de thi T S DH, C B Mon Vat li Giai Mufc CLfcfng a m ban dau: L, = lOlg — Mufc cufdng a m k h i h = l O I i : L2 = 1 g ^ Ta c6: L ^ - L , = lOlg — - l O l g ^ - lOlg-^ = lOlglO = l O ( d B ) ^0 ^0 ^1 Vay chgn dap an C Cdu 4: B a n dau ( t = 0) c6 m o t mau chat phong xa X nguyen chat O thdi diem t i mau chat phong xa X l a i % h a t n h a n chtfa b i p h a n D e n thcfi d i e m t2 = t i + 100 (s) so h a t n h a n X chtfa b i p h a n r a c h i 5% so v d i so h a t n h a n ban dau Chu k i b a n r a ciia chat phong xa l a : A 25 s B 200 s C 50 s D 400 s Giai T a i thofi diem t i : N„ ii N _ 20%No OAO/.M _ N, = -_0f = =—^=>2T =5 (1) T a i tho-i diem ts = t i + 100: N„ 1, + lUO N N2=-TTlW = % N „ = - f ^ 2 ' =20 (2) T f'iil^.lil Chia (2) cho (1) t a diXtfc: 2^ ^ ,AA = - 2" => - ^ ^ = « T = 50(s) Vay chon dap an C Cdu 5: D u n g h a t p r o t o n c6 dong n a n g 1,6 M e V b a n vao h a t n h a n U t i ( j L i ) dufng yen Gia suf sau p h a n ufng t h u dUgfc h a i h a t giong c6 cung dong n a n g va k h o n g k e m theo t i a y B i e t n a n g liiofng t o a r a cua phan ufng l a 17,4 MeV Dong n a n g ciia m i h a t s i n h r a l a : A 15,8 MeV B 19,0 MeV C 7,9 MeV D 9,5 MeV Giai Trong triTcfng hcfp k h o n g k e m theo t i a y, theo d i n h luat bao toan nang Itfdng, t o n g dong n a n g cua h a t s i n h r a p h a i bfing n a n g lifcfng cua Giai Chi tiet de thi TS DH, CD Won Vat If 85 p h a n ufng t o a r a cpng vdri dong n a n g b a n dau Theo do, neu goi K la n a n g lufcfng cua m i h a t t h i t a c6: K = 17,4 M e V + 1,6 M e V = 19 M e V ^ K = 9,5 MeV Vdy chgn dap an D Cdu 6: M o t k h u n g day d i n phSng det h i n h chOr n h a t c6 500 vong day, dien t i c h m o i v o n g l a 220 cm^ K h u n g quay deu v d i toe 50 vong/giay quanh m o t true doi xufng n a m t r o n g m a t p h i n g cua k h u n g day, m o t tCr trtroTng deu c6 vectcf cam ufng tCf B vuong goc vdti true quay va eo Idfn — T Suat d i e n dong cire d a i t r o n g k h u n g day bang: 571 A 2 V V B 220 V C I I O V V D I I O V Giai Suat d i e n dong ciic d a i t r o n g k h u n g day b k n g : f? E g = coNOo = coNBS = 271.50.500.—.200.10-'= 2 ^ / ( V ) 571 Vdy chgn dap an A Cdu 7: M o t stfi day A B c6 chieu d a i m cang ngang, dau A co dinh, dau B gSn vdri m o t n h a n h cua a m thoa dao dong dieu hoa vdfi t a n so 20Hz T r e n d a y A B eo m o t song dCrng o n d i n h vdri bung song, B ducfc eoi l a n u t song Toe t r u y e n song t r e n day l a : A 50 m/s • B 2,5 cm/s C 10 m/s D cm/s Giai H a i dau A B dirde eoi l a n i i t song Do vay t r e n day c6 m u i song Ta c6: I = 4-^2X=>X =- = 0,5(m) Toe t r u y e n song: v = ^if = 0,5.20 = 10(m/s) Vdy chgn dap an C Cdu 8: M o t nguon sang c h i p h a t r a a n h sang dcfn s^c eo t a n so 5.10^^Hz Cong suat bufe xa dien tCf cua nguon l a l O W So photon ma nguon p h a t r a t r o n g m o t giay x a p x i hkng: A 0,33.10^^ B 3,02.10^° C 3,02.10^^ 86 D 3,24.10^^ Giai Chi tigt 66 thi TS DH, CD M6n V$t II Giai So photon m a nguon p h a t r a t r o n g m o t giay x a p x i bang: N =— = ~ - r « 3,02.10'^ hf 6.625.1(r'-'.5.10'-' Vay chgii dap an C Cdu 9: Theo thuyet luang tijf a n h sang, p h a t bieu nao dvidi day la sai? A P h a n tijf, ngiiyen tuf phat xa h a y h a p t h u a n h sang, cung c6 nghia la chung phat xa hay h a p t h u photon B A n h sang diioc tao t h a n h bdi cac h a t goi l a p h o t o n C N a n g iLfgtng ciia cac photon a n h sang l a nhtf nhau, k h o n g p h u thuoc t a n so' ciia a n h »ang D T r o n g chan k h o n g , cac photon bay doc theo t i a sang v d i toe c = 3.10^m/s Giai N a n g lifcJng cua cAc photon s = h f n e n t a n so a n h sang khac thi nSng li/cfng e khac Vay chgn dap an C Cdu 10: D a t dien ap u - Uocoscot c6 co thay doi dixac vao h a i dau doan mach gom cuon cam t h u a n c6 t\i cam L , di$n t r d t h u a n R va t u dien CO dien dung C mSc n o i tiep K h i co < J — thi: VLC A ciidng dong dien t r o n g doan mach cung pha v d i dien a p giufa hai dau doan mach B dien ap hieu dung giufa h a i dau dien trcf t h u a n R n h o h o n dien ap hieu dung giufa h a i dau doan mach C cUdng dong dien t r o n g doan mach tr§ pha so vdri d i e n ap giufa hai dau doan mach D dien ap hieu dung giffa h a i dau dien t r d t h u a n R b a n g d i e n ap hieu dung giu:a h a i dau doan mach Giai Khi CO < t h i Z , - Zp > Khi Z = ^ R ' + ( Z , - Z , ) ' > R Suy r a U R < U Vay chgn dap an B G\iii Chi ti^t de thi T S D H , C D Mon Vat li 87 Cdu 11: T r o n g scf k h o i cua m o t may phat t h a n h dung song v6 tuyen k h o n g C O bo p h a n nao diTdfi day? D Anten C M a c h khuech d a i B M a c h tach song A M a c h b i e n dieu T r o n g scf k h o i cua m o t m a y phdt t h a n h dung song v6 tuyen, k h o n g can bo p h a n tach song Vdy chon dap an B Cdu 12: Song d i e n tCf A C O t h a n h p h a n dien tnfcfng va t h a n h phan tCf triTdng t a i mot diem dao dong cung phi/cfng B la d i e n tCr trLfomg Ian t r u y e n k h o n g gian C l a song doc hoSc song ngang D k h o n g t r u y e n dtfcfc t r o n g chan khong GiSi Song d i e n tCr l a song ngang, t r u y e n diTcfc t r o n g chan k h o n g va k h i t r u y e n t h l vectcf E va B luon vuong goc vdfi Vdy chgn dap an B, Cdu 13: M a c h dao dong l i t i i d n g gom cuon cam t h u a n c6 i\S cam L va tu d i e n c6 d i e n dung C dang thifc h i e n dao dong dien tCf tiT Goi Uo l a d i e n ap ciic d a i giufa h a i ban t u ; u va i la dien ap giufa h a i ban t u va ciTcfng dp dong d i e n t r o n g mach t a i thofi diein t He thufc d u n g l a : D i ^ = ^ ( U ^ u ^ ) C.i^=LC(U^u^) B i ^ = ^ { U ^ u - \ ) A i ^ = V L C ( u ^ - u = ) Giai A p dung d i n h l u a t bao t o a n n a n g liTong cho mach L C , t a c6: -CU^ =-CU^+lLi^ o i ^ =-(u^-ir) Vdy chgn dap an B Cdu 14: M o t v a t dao dong dieu hoa v(5fi bien cm Moc the nSng d v i t r i can b^ng K h i v a t c6 dong nkng b k n g ^ I a n ccf n a n g t h i v a t each v i t r i can bSng m o t d o a r A 4,5 cm B cm C cm D cm Giai chi tiet cJe thi T S OH, C D M6n VSt 1( 88 Gial K h i dong n a n g bSng — ccf n a n g t h i the n a n g bang: Wt = W - Wd = W - - W = - W 4 K h i t a c6: - k x " = - - k A " x = — x = — = ( c m ) 4 ^ ^ Vay chgn dap an D Cdu 15: Dat dien ap xoay chieu u = CO dien UQCOS cot vao h a i dau doan mach chi t r d thuan Goi U la dien ap hieu dung giOfa h a i dau doan mach; i, lo yk I Ian liJc/t l a gia t r i tilc t h d i , gia t r i cua CLTcfng dai va gia t r i hieu dung dong dien t r o n g doan mach He thufc nao sau day A - ^ - = Uo C L T C sai? B.-^-i.O lo U C — + — = D +— = yjl Giai Tac6: _ ^ Jo_ V2U0 V2I0 ^0 ^^'0 U„ u i _ uV2coscot ij~T~ U Uo V2 l>^coscot u I • 1 lo V2 72 V2 = • + — = —p= + - Vdy chqn dap an C Cdu 16: T r o n g cac loai t i a : Rcfn-ghen, h o n g ngoai, tuf ngoai, dofn sac mau luc; t i a c6 t a n so nho n h a t l a : A t i a h o n g ngoai ' B t i a Rcfn-ghen; C t i a dofn sAc mau luc D t i a tuf ngoai Giai T i a h o n g ngoai c6 bifdc song I d n n h a t nen c6 t a n so nho n h a t Vay chgn dap an A Cdu 17: D ^ t dien ap xoay chieu vao h a i dau doan mach gorh d i e n t r d thuan Q va t u dien mic n o i tiep B i e t dien ap giufa ha^.dau doan Giai Chi tiet tie thi T S B H , C D Mon Vat li 89 mach lech pha y so vdi cifcfng dong dien doan mach Dung khang ciia tu dien bkng: A 40V3Q B 20V3Q C 40Q Giai Do lech pha: tancp = R Zc = tan-o ^ = V3 « Z"^ = R V = 40V3 ( Q ) R Yay chon dap an A • ' Cdu 18: Hieu dien the giufa hai dien cifc cua ong Cu-lit-gitf (ong tia X) la UAK = 2.10^V, bo qua dong nang ban dau cua electron k h i buft khoi catot Tan so Idn nhat cua tia X ma ong c6 the phat xap xi bang: D 4,83.10'^ Hz C 4,83.10'^ Hz B 4,83.10^' Hz A 4,83.10^^ Hz Giai Ta c6: eU = hf =^ f - 6,625.10-'-' h 1,6.10-".2.10' eU = 4,83.10" Vay chon dap an C Cdu 19: Mot song ccf truyen mot moi tri/dng doc theo true Ox vdi phirctog t r i n h u = Scos(67rt-7rx) (cm) (x tinh bSng met, t tinh hkng giay) Toe truyen song bang: A m/s D i m/s C - m/s B m/s GiSi So sanh phi/orng t r i n h song u = 5cos(6;rt-7tx) vdri phiTorng trinh tong quat u = UQ COS cot (0 ta thay: co = 671; — = 7i X V Taco: v = - = — = 6(m/s) 71 71 Vay chon dap an B Cdu 20: Trong so cae hanh tinh sau day cua he Mat Trori: Thuy tinh, Trai Dat, Tho t i n h , Moc t i n h ; hanh tinh xa Mat Trcfi nhat la A Moc t i n h B Thuy tinh C Tho tinh D Trai Dat Giai Chi tiet d e thi T S D H , CO M n V | t l( 90 Giai Trong so cac h a n h t i n h t h i Tho t i n h xa M a t Tro'i n h a t Vay chgn dap an C Cdu 21: K h i n o i ve song am, phat bieu nao sau day la s a i ? A Song a m t r o n g k h o n g k h i la song ngang B Song a m t r u y e n dxiac t r o n g cac m o i trUdng rAn, l o n g va k h i C Song a m t r o n g k h o n g k h i l a song doc Cling m o t n h i e t do, toe t r u y e n s o n g a m t r o n g k h o n g D d nho han toe t r u y e n s o n g a m nUdc Giai Song a m t r o n g k h o n g k h i la song doc n e n p h a t bieu A sai Vay chgn dap an A Cdu 22: N g u y e n tijf h i d r o chuyen ttf t r a n g t h a i dUng c6 n a n g l u g n g En = - l , e V sang t r a n g t h a i dCfng c6 nSng l i i o n g E m = -3,4eV Budtc song cua bufe xa ma nguyen tiu h i d r o p h a t r a xap x i b k n g : A 0,654.10-^ m B 0,654.10-^ m C 0,654.10"^ m D 0,654.10"^ m Giai Taco:—= E2-E, ^ , ^ _ ^ - E^-E, 3^^^ (1,5 + 3,4)1,6.10"" Vay chgn dap an B Cdu 23: M o t iSc 16 xo gom v i e n b i nho va 16 xo nhe c6 cufng lOON/m, dao dong dieu h6a vdfi b i e n 0,1 m Mo'c the n a n g d v i t r i can bang K h i v i e n b i each v i t r i can bSng cm t h i dong n a n g cua eon l^c bang: A 0,64 J B 0,32 J C 3,2 m j D 6,4 m J Giai Ccf n a n g cua l^c: W = ^ k A ^ The nSng cua lac k h i each v i t r i can h^ng 6cm: W=-k.6.10-' ' Giai Chi ti^t 66 thi T S B H , C D Mon Vat If 91 Dong n a n g cua lac k h i do: Wd = W - Wt = - 0 ( - ' ) ' - { - ' ) ' = 0.32J Vay chgn dap an B Cdu 24: DSt d i e n ap u = 2 V c o s l 0 t t (V) vao h a i dau doan mach A B g o m ' h a i d o a n m a c h A M va M B mSc n o i t i e p D o a n A M gom d i e n tror t h u a n R mSc n o i t i e p vdfi cuon cam t h u a n L, doan M B chi CO t u d i e n C B i e t d i e n ap giufa h a i dau doan m a c h A M va d i e n ap giufa h a i dau d o a n m a c h M B c6 gia t r i hieu d u n g b ^ n g nhUng lech pha — Dien ap hieu dung giCfa hai dau doan mach A M bkng: A 110 V C 220 V2 V B 220 s V AM D 220 V Giai Diia vao de b a i , t a c6 g i a n vector nhtf h i n h ve Diia vao g i a n vector t a c6 the t h a y UAM = UAB = U C = 220 (V) Vay chqn dap an D Cdu 25: K h i m o t v a t dao dong dieu hoa t h i A liJc keo ve tac dung len vat c6 Idn ciic dai k h i vat vi t r i can bkng B v a n toe cua v a t c6 Idn ciSc dai k h i v a t of v i t r i can bkng C gia toe cua v a t c6 Idfn c\Xc dai k h i v a t d v i t r i can bang D liic keo ve tac dung len vat c6 Idn t i le vdri b i n h phiidng bien Giai K h i m o t v a t dao dong dieu hoa t h i v a n toe cua v a t c6 Idn cxlc dai k h i v a t d v i t r i can bang Vay chon dap an B Cdu 26: M o t l a n g k i n h t h u y t i n h c6 goc chiet quang A = 4°, dat k h o n g k h i C h i e t suat cua l a n g k i n h doi v d i a n h sang va t i m Ian lUgrt 1^ 1,643 va 1,685 Chieu mot chijm t i a sang song song, hep gom hai bufc xa va t i m vao m a t ben eua l a n g k i n h theo phiicfng vuong goc v d i m a t Goc tao bdi t i a va t i a t i m sau k h i 16 r a k h o i mat ben k i a ciaa l a n g k i n h xap x i bang: A 0,336° B 1,416° C 13,312° 92 D 0,168° Giai Chi ti6't de thi TS DH CD M6n Vat li Giai Goc l e c h cua t i a s a n g d o : D i = A(nd - 1) = ( , - 1) = 2,572° Goc l e c h cua t i a s a n g t i m : Dg = A(nt - 1) = ( , - 1) = 2,74° Goc l e c h giffa h a i t i a : A D = Dz - D i = 2,74 - , = 0,168° Vay chgn dap an D Cau 27: T a i m o t n o i t r e n m a t d a t , l a c dofn c6 c h i e u d a i C d a n g dao dong d i e u h o a v d i c h u k i 2s K h i t a n g c h i e u d a i c u a c o n iSc t h e m c m t h i c h u k i dao d o n g d i e u h o a cua n o l a 2,2s C h i e u d a i t b a n g : A 2,5 m B m C m D 1,5 m Giai B a n d a u , c h u k i dao d o n g c u a c o n l&c l a : T, =271 - = 2(s) (1) Sau k h i t a n g t h e m c m , c h u k i dao d o n g c u a c o n ISc l a : T,=2.Alil=2.2(s) (2) TCr (1) v a (2) t a c6: = 1.1- = , t = —+ — T 2) T h d i d i e m dau t i e n (ke tCf t = 0) dien t i c h t r e n b a n t u bang T la — Vdy chon dap an D Cdu 28: D a t dien ap xoay chieu vao h a i dau doan mach gom dien troT t h u a n , cuon cam t h u a n va t u dien mac no'i t i e p B i e t cam k h a n g cua cuon cam b ^ n g I a n dung k h a n g cua t u dien T a i thori diem t, dien ap tufc t h d i giufa h a i dau dien trcf va dien ap tufc thori giiifa h a i dau tu dien c6 gia t r i tiTcfng ufng la 60 V va 20 V K h i dien ap tufc t h i giffa h a i dau doan m a c h l a A 20^/T3V B loVis V C 140 V D 20 V Giai Do Z L = 3Zc n e n k h i uc = 20V t h i UL = - V (vi UL va uc luon ngiftfc pha nhau) Suy r a : u = UR + UL + uc = 20V Vdy chgn dap an D Cdu 29: D a t d i e n ap u = Uocos((ot + (p) vao h a i dau doan mach gom dien trdr t h u a n R va cuon cam t h u a n c6 t i i cam L mac noi tiep He so cong suat cua doan mach l a coL R B A C R VR'+W ' R D (oL coL 7R'+(COL)' 182 Qi&i Chi tl^t TTNVdy chgn Cdu 48: dap an B M o t m a y p h a t d i e n x o a y c h i e u m o t p h a c6 p h a n c a m l a r o t o v a so c a p cifc l a p PQii r o t o q u a y d e u v ( i i toe n ( v n g / s ) t h i t t f t h o n g q u a m o i c u o n d a y c u a s t a t o b i e n t h i e n t u a n h o a n v d i t a n so ( t i n h theo ddn v i Hz) la A ^ 60 B C p n 60p D.pn Giai Tan so f = p n Vdy chgn Cdu dap an D 49: T r o n g t h i n g h i e p Y - a n g v e g i a o t h o a vdri a n h s a n g dcfn sSc, k h o a n g e a c h giiJa h a i k h e l a m m , k h o a n g each tCr m S t p h S n g ehufa h a i k h e d e n m a n q u a n s a t l a m T a i d i e m M t r e n m a n q u a n s a t each v a n s a n g t r u n g t a m m m c6 v a n s a n g bac Bu'dfc s o n g eua a n h s a n g d u n g t h i nghiem la A , ^ m B 0,45^m C , n m - 88 D 0,75^m Giai Chi tiet de thi TS DH, CD Mon VSt li V i t r i v a n sang^tren m a n quan sat x = k XD a X = ax = 0,5 i^im kD Vay chon dap an A Cdu 50: T r e n m o t sgri day c6 song dCrng v d i bifdc song la X Khoang each giuTa h a i n u t song l i e n ke la A.i B 2X D X Giai Khoang each giufa h a i n u t song l i e n ke la — Vay chon dap an A Cdu 51: M o t v a t vkn dang quay quanh m o t true co d i n h xuyen qua vat Cac d i e m t r e n v a t rSn (khong thuoe true quay) A CO eung gia toe goc t a i cung m o t thori d i e m B CO eung toe d a i t a i cung m o t thcfi d i e m C quay di/gfc nhOfng goc khac t r o n g cung m o t khoang thofi gian D CO toe goe khae t a i eung m o t thc?i d i e m Giiii Cac d i e m t r e n v a t r ^ n (khong thuoe true quay) A co eung gia toe goe t a i C l i n g m o t thcfi d i e m Vay chon dap an A Cdu 52: M o t t h a n h cuTng, nhe, chieu dai 2a T a i m i dau ciia t h a n h CO gSn mot v i e n h i nho, k h o i luong cua m i v i e n h i la m M o m e n quan t i n h cua he ( t h a n h va cac v i e n hi) doi vdri true quay d i qua t r u n g d i e m cua t h a n h va vuong goc v d i t h a n h la A m a l B -ma^ C m a l D -vaa? Giai Ta co: I = ma^ + ma^ = 2ma^ Vay chon dap Cdu 53: an A B i e t dong n&ng tiicfng doi t i n h cua m o t h a t b a n g nang lUcfng n g h i cua no Toe cua h a t ( t i n h theo toe a n h sang ehan k h o n g c) b ^ n g A.ic GA\i tilt 04 thi TS DH, CD Mon Vat I 189 Ta CO E = Eo + Wd = 2Eo Suy r a : V rtioC- GiSi mc^ = 2moC^ = 2moC^ => - = 1- - ^ V = c Vdy chpn dap an C Cdu 54: T a i m a t chat l o n g c6 h a i nguon p h a t song k e t hgfp S i va S2 dao dong theo phifcrng vuong goc v d i m a t chat l o n g c6 cung phi/cfng t r i n h u = 2cos40 7it ( t r o n g u t i n h bSng cm, t t i n h b a n g s) Toe dp t r u y e n song t r e n m a t chat l o n g l a 80cm/s G o i M l a diem t r e n mSt chat l o n g each S i , S I a n Itfcft l a 12cm va 9cm Coi b i e n cua song t r u y e n tCr h a i nguon t r e n den d i e m M l a k h o n g doi P h a n tuf chat long t a i M dao dong v6i b i e n l a A V c m B V c m C cm D cm Giai Biidc song X = —• = — ^ f 20 = cm Song t r u y e n tCr S i va S2 tcSi M c6 bieu thufc: •VIM = 2cos t - 27t.d, ; U2M = 2cos - B i e n song t a i M : A M = 4cos 7r(d,-d,) I- 27t.d, \ X = |4cos 371 = V cm Vdy chgn dap an B Cdu 55: T r o n g so cac hat: proton, anpha, t r i n i vk dcfteri, hat so cap la A t r i n i B dorteri C anpha D proton Giai Chgn dap an D: P r o t o n Cdu 56: K h i n o i ve m o t v a t dang dao dong dieu hoa, p h a t bieu nao sau day dung? A Vector gia to'c cua v a t d o i chieu k h i v a t c6 l i ctic d a i B Vector v a n toe va vectcf gia toe cua v a t cung chieu k h i vat chuyen dong ve p h i a v i t r i can b a n g C Vectcf g i a toe cua v a t luon hirdtng r a xa v i t r i can b&ng D Vector v a n toe va vectcf gia toe cua v a t cung chieu k h i vat chuyen dong r a x a v i t r i can bang Giai Chi tiet 90 thi TS DH, CO M6n VSt li Giai Vay chgn dap an B: K h i v a t chuyen dong n h a n h dan Cau 57: T r o n g song dien tijf, dao dong cua d i e n t r i l n g v& cua tCr tnfcfng t a i m o t diem luon luon A ngifoc pha B lech pha ^ C dong pha D lech pha ^ Giai Dao dong cua dien trtfdng va cua tCf trifdng t a i m o t d i e m luon luon dong pha Vay chgn dap an C Cdu 58: Chieu bufc xa d i e n ttf c6 bilcSc song 0,25 fim vao catot cua mot te bao quang dien c6 gidri h a n quang d i e n la 0,5 ^ m Dong n a n g ban dau ctfc d a i cua electron quang dien la A 3,975.10-2°J B 3,975.10-"J C 3,975.10-'^J D 3,975.10-i'J Giai Ta c6: ^ = ^ + Waon.ax => W^o^ax = ^ - ^ = 3,975.10-^^J Vdy chgn dap an C Cdu 59: M o t v a t r a n dang quay n h a n h dan deu quanh m o t true co dinh xuyen qua v a t M o t d i e m t r e n v a t rSn (khong thuoc true quay) c6 A vectof gia toe t i e p tuyen hifdfng vao t a m qui dao cua no B I6n gia toe tiep tuyen k h o n g doi C vectcf gia toe t i e p tuyen nguTOc chieu vdri chieu quay cua no d m o i th&i diem D lorn gia toe tiep tuyen t h a y doi GiSi Chgn dap an B Cdu 60: M o t v a t r a n quay quanh dan deu tCf t r a n g t h a i n g h i quanh mot true CO d i n h xuyen qua v a t Sau 4s dau t i e n , v a t r S n dat toe goc la 20 rad/s T r o n g thcfi gian do, mot diem thuoc v a t rSn (khong n ^ m t r e n true quay) quay difOc mot goc c6 16'n b k n g A 40 r a d B 10 r a d C 20 r a d D 120 r a d Giai Chgn dap an A Giaichitigt[...]... l a : 20 9,937303u; 4,001506u; MeV 20 5, 929 442u v a l u = 931,5 — — N a n g liTcfng t o a r a k h i m o t h a t n h a n c poloni p h a n r a x a p x i bang: D 2, 96 MeV C 5, 92 M e V B 29 ,60 MeV A 59 ,20 M e V Giai Do h u t k h o i : Am = mp^ - (n^Pb + ) = 20 9,937303U - 20 5, 929 442u -4,001506u = 0,006355u AE = A m c ' = 5 , 9 1 9 6 8 2 5 « 5, 92 MeV Vay chgn dap an C Cdu 52: M p t scfi d a y chieu d... coi, CO2 va coo l a : A C0o=-(co^+co^) 1 C 1 COQ = -y/c0|C 02 D- C0o-^(co,+co2) 1 vco- COn B co;^ GiSi K h i CO = coi hoac co = C 02 ta co: C| c, c, C2 7 ^1 7 "-^ ^2 1 1 (0,/ co,L co,C, co;.R"+co,.L co,L- CO, 2co;L 1 c c =—+ co,C, 2 =co^R'+co;.L'- (co;-co^) L / 9T > w6i R'< 1 = L-(cof-co^) (cof-co2) = L-(co;'-co2) 2L - R ^ 2co?L (1) — 2L _ C M a t khac (Uc)max theo co k h i COQ = • L a y (2) ... dao dCrng n = 5 ve quy dao diTng n = 2 t h i nguyen tuf phat ra photon c6 biTdrc song M o i l i e n he giCfa h a i birdrc song \a 1, la: D C 189?., = 8 0 0 X , B 2 7 ? i 2 = 128 X, A = 4\ = 5\ Giai T a c6: X, he = 2 ^ 1 ^ E 3 - E , ^ =- E„ 25 0 E„ ^ (1) 0 21 4 (2) 100 8E„ L a y (1) chia cho (2) t a c6: ^2 800 _ X, 21 Eo 189 =^mX2 =800\ 100 Vdy chon dap an C Cdu 24 : Neu n o i h a i dau doan mach gom... do la: A 2. 10-^s B 3.10-''s C e.lO-^s D 12. 10-*s Giai Ta c6: 2C 2 2C •" V2 ' T h d i gian nang liicfng dien g i a m tCf ctfc d a i xuong m o t nufa bang thdi gian q g i a m tCr Q Q —> : '• 71 t = -:^ = ^ 27 1 2TC T Y = - 8 = l , 5 1 0 - ' s = > T = 12. 10-^8 Thc/i gian de d i e n t l c h g i a m tii cUc dai xuong m o t nufa: t = ^ = i = I = 2. 10-s CO 27 t 6 T Vdy chon dap an A Giii Chi ti6t dS thi T S... c o : Ad = 4 , 5 - 2 = 2 , 5 ( m m ) So khoang v a n : n = 2 5 1 ,2 « 2 v a n (n nguyen) Vay ta chi quan sat dticfc 2 v a n sang (each v a n t r u n g t a m 2, 4mm va 3,6mm) va 2 v a n t o i (each v a n t r u n g t a m 3 m m va 4,2mm) Vay chgn dap an D Cdu 39: M o t dong ccf k h o n g dong bo ba pha mac theo k i e u h i n h r.ao dUcfc noi vao mach dien ba pha c6 dien ap pha Upha = 22 0V Cong suat dien... : A , 2, 41.10^nVs B 2, 24.10Vs C 1 , 6 7 l O W s ' D 2, 75.10Ws Giai T a c o : Wd = E - E o = ^Eo^E=^Eo 1 12 Giai Chi m de thi TS DH, CD M6n Vat li 2 -i = - m o c ' « v = 2, 24.10'm/s 1Vdy chgn dap an B Cdu 17: Mot con lit dan difcfc treo vao tran mot thang may K h i thang may chuyen dong thang dufng di len nhanh dan deu vdi gia toe c6 do Idfn a t h i chu k i dao dong dieu hoa cua con lac la 2, 52s K h... dai t h i m i den v i t r i bien A', th6i gian dao dong la: 4 4o)' 2to' Vm co.2v2 Trong th6i g i a n n a y , m2 di difgrc: s = v At = v^^.At = c o A — w 71 .2 V2 cm a).2V2 K h i do k h o a n g e a c h giuTa h a i v a t l a : Ad = s - A ' « 3 , 2 ( c m ) Vay chgn dap an B "IIS Giai Chi tigt (J« thi TS BH, CB M6n V$l l( Cdu 29 : Dao dong cua mot chat diem c6 khoi ItfcJng 100 g la tong htfp cua hai dao... lifcft dat cac dien ap xoay chieu u i = U cos(1007it + 9 1); U2 = U V2 cos( 120 7it + 9 2 ) va U3 = u V 2 cos(1107it + 9 3 ) vao hai dau doan mach gom dien t r d thuan R, cuon c%m thuan co do tiT cam L va tu dien CO dien dung C mSc noi tiep t h i ciTcfng do dong dien trong doan mach CO bieu thufc tufctog ufng la: i i = I V 2 coslOO;tt; i2 = I V 2 cos( 120 7tt + ^ ) va k = r V 2 c o s ( 1 1 0 7 t t - y ^... Gia t r i eua U l a : A 400 V B 20 0 V Giii Chi l\6t 06 thi TS DH, CD M6n V$t li C 100 V2 V D 100 V 1 03 Giai K h i cong suat tieu thu trong doan mach hang nhau, ta c6: z 20 ^+Zl 20 r - =- O 8 0 + Z'L 80 20 '+Zl 1 SO + Zl 4 « 2 0 ' 4 + 4 Z ' ^ = 8 0 + Z'L « 3 Z [ •= 4 8 0 0 ^ Taco: P(Rf+zM U ' - - ^ ^ ^ R, ^ = ZL = 40(Q) 400(400 + 1600) ^ = 40000 =^ U = 20 , , 20 0(V) ^ ^ Vay chgn dap an B Cdu 57:... ciromg do dong dien i = 0,12cos2000t (i t i n h bang A, t tinh hkng s) O th6i diem ma ciXbng do dong dien trong mach bkng mot nufa cUong do hieu dung t h i hieu dien the giufa hai ban tu c6 dp \dn bkng: A 3 V i 4 V B 6 V 2 V C 12> ;^ V D 5 V l 4 V Giai Ta c6: - L i - + - C u ' = - L l ^ Suy ra: 2 u= 2 2 = » L V l T ^ = 20 00.50.1^0, 12^ -[^^^j = 3Vl4 V Vdy chgn dap an A Cdu 27 : Phat bieu nao sau day