Hướng dẫn giải chi tiết đề thi tuyển sinh đại học, cao đẳng môn Vật lý giới thiệu tới người đọc các phương pháp giải bài tập Vật lý một cách nhanh chóng, chính xác, giúp người học có thể vận dụng nhanh trong quá trình làm bài thi. Mời các bạn cùng tham khảo.
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