Hướng dẫn giải chi tiết đề thi tuyển sinh ĐHCĐ môn vật lý (NXPowerLite copy)

530.076 PHAN VAN HUAN H561D HlidNG DAN GIAI CHI TIET DE THI TUYEN SINK DAI HOC CAO B&NC VAT LI H Nha xuat ban Dai hoc Quoc gia Ha NOi bJO 01± '-W5t>/< PHANVANHUAN DE THI DAI HQC - CAO DANG M6n VAT LI NHA XUAT BAN DAI HQC QUOC GIA HA NQI N H A X U A T B A N DAI H Q C Q U O C G I A H A NOI 16 HANG CHUOl - HAI BA T R U N G - HA NOI Dien thoai: Bien tap - Che b a n : (04) 39714896 Hanh chi'nh: (04) 39714899 Tonq bien t a p : (04) 39714897 Fax: (04) 39714899 Chiu trach nhi$m xuat ban: Giam doc - Tdng bien tap: tap: PHAM TH! TRAM Nha sach S A O MAI Doi tac lien l Vi Neu chieu dong t h d i h a i bufc xa t r e n v^o qua cau t h i d i $ n the cifc dai cua no chi hang d i e n the I d n hcfn, c h i n h la V2 Vdy chon dap an A Cdu 2: T r o n g t h i n g h i e m ve song dCrn^, t r e n m o t stfi day d a n h i d^i 1,2 m v d i h a i dau co d i n h , ngUdi t a quan sat t h a y ngoai h a i dau day co d i n h co h a i d i e m khac t r e n day k h o n g dao dong B i e t k h o a n g t h d i gian giOfa h a i I a n l i e n tiep sgti day duoi t h i n g l a 0,05 s V a n toe t r u y e n song t r e n day l a : A 16 m/s B m/s C 12 m/s D g m/s Giai Theo de b a i t h i t r e n day tao t h a n h m u i song, m o i m i i i s6ng co chieu dai — T a c o : - = 1,2 = > = 0,8m Khoang t h d i gian giffa h a i I a n l i e n t i e p stfi day a j j t h i n g l a 0,05s nen t a co chu k i T = 0,05.2 = 0,1s V a n toe t r u y e n song t r e n day: ^ 5i, = ^ ~ "QT ~ ^C™'^)' Vdy chon dap an D Cdu 3: Doi v d i SLT Ian t r u y e n song dien tCf t h i A vector ciTdng dien triJdng E va vectcf cam ufng tCr B luon vuong goc v d i phtTcfng t r u y e n song Giai Chi tiSt (3e thi TS DH, CO M6n vat li B vectcf CLfcrng d i e n triTcfng E va vecto cam ufng tiT B luon cung phiiong vdfi phiTctog t r u y e n song C vector cam ufng tif B cung phLfcrng vdri phirorng t r u y e n song vector CLTcfng dien t r i / d n g E vuong goc v d i vector cam ufng ttf B D vectcf cifcfng dien tn/cfng E cung phtfcfng v6i phiromg truyen song c6n vector cam ufng tCf B vuong goc vdri vector ci/orng dien trUdng E Giai D o i v d i suf Ian t r u y e n song dien tCf t h i vecto cifdng dien triicfng E va vector cam ufng tCr B luon vuong goc vdri phiTorng t r u y e n song Vay chgn dap an A Cdu 4: Cof n a n g cua m o t v a t dao dong dieu hoa: A t a n g gap doi k h i bi§n dao dong cua v a t t a n g gap doi B b i e n t h i e n t u a n hoan theo t h d i gian v i chu k y b k n g chu k y dao dong cua v a t C b i e n t h i e n t u a n hoan theo thofi gian v d i chu k y bSng mot nufa chu k y dao dong cua vat D b a n g dong nSng cua v a t k h i v a t id'i v i t r i can bang GiSi Cor n a n g cua m o t vat dao dong dieu hoa bang dong nang cua vat k h i v a t tdri v i t r i can bang Vay chgn dap an D Cdu 5: H a t n h a n '°Be c6 k h o i liTcrng 10,0135u K h o i lifgng cua ncftron ( n a t r o n ) m n = l , 0 u , k h o i Itrcrng cua p r o t o n ( p r o t o n ) mp = l , 0 u , l u = 931 MeV/c^ N a n g liTcfng l i e n k e t r i e n g cua h a t n h a n '"Be D 632,1531 MeV C 6,3215 M e V B 63,2152 MeV A 0,6321 M e V la: Giai N a n g Itfdng l i e n k e t r i e n g cua h a t n h a n '°Be l a : «' AC (6m„+4m -meJ.QBl AJb^V ^ = 6,3215MeV A Vay chgn dap A an C Cdu 6: P h a t bieu nao sau day la s a i k h i n o i ve nang liidng dao dong dien tii t i i (Jo (dao dong rieng) t r o n g mach dao dong dien tCr LC k h o n g CO dien trcf thuan? Giai Chi tiet de thi TS DH, CD M6n Vat li A tl^.ng luang tCr trifcfng cure dai b k n g n a n g Itfong d i e n tCr cua mach dao dong B N a n g Itfcfng dien trtf&ng va n a n g Itftfng tCr t n f o n g b i e n t h i e n dieu hoa vdfi t a n so bSng mot nijfa t a n so cua ctfcfng dong dien t r o n g mach C K h i nSng lifcfng dien trtfcrng g i a m t h i n a n g liitfng tCr trifcrng t a n g D Nang Itfofng dien tii cua mach dao dong bkng tong nang liigfng dien tnfcfng tap trung cf t u dien va nang li/cfng tCr tnicfng tap trung cf cugn cam Giai V i n a n g lifcfng dien triicfng va nSng Itfofng tCf triXdfng b i e n t h i e n dieu hoa v6i chu k i bang mot nufa chu k i cifcfng dong dien t r o n g mach nen tan so cua no p h a i gap doi t a n so cua cifdfng dong dien t r o n g mach Vdy chqn dap an B Cdu 7: T i a Rcfnghen c6 A cung b a n chat v i song v6 tuyen B cung ban chat vdfi song a m C dien t i c h a m D btfdfc song Idfn hcfn biTdfc song cua t i a h o n g ngoai Giai T i a Rcfnghen la bufc xa dien tii n e n k h o n g m a n g d i e n , c6 cung b a n chat vdfi song v6 tuyen va c6 bildfc song nho hofn biidfc song cua t i a hong ngoai Vdy chon dap an A Cdu 8: H a t n h a n A dang dufng yen t h i p h a n r a t h a n h h a t n h a n B c6 k h o i lifong ms va h a t a c6 k h o i lucfng m„ T i so giOfa dong n a n g cua h a t n h a n B va dong n a n g cua h a t a sau p h a n r a b k n g : A ^ c B m„ D ^ Giai Ap dung d i n h l u a t bao toan dong liJcfng cho h a t dang dufng y e n , t a c6: mBVB = m„v„ T i so giufa dong n&ng cua h a t n h a n B va dong nSng cua h a t a sau p h a n r a l a : ^ Vdy chqn dap an D Giai Chi tiet de thi T S B H , C D M6n Vat II = - Cdu 9: Cho doan mach di$n xoay chieu gom cuon day c6 dien trd thuan R , m^c nol tiep v6i tu*dien Biet hieu dien the giffa hai dau cuon day lech pha — so v6i hi|u dien the giuTa hai dau doan mach Moi lien h$ giiJa dien tror thuan R vdri cam khang Z L cua cuon day dung khdng Zc cua tu dien la: ' D R=^ = ZC(ZL - C R ' = Zc(Zc - ZL) ' E R2 = ZL(ZC - Z L ) A R ' = ZL(ZL - Zc) Zc) Do lech pha giffa hai dau cuon day: tancp, = —^ R Z Do l$ch pha giffa hai dau doan mach: tan(p = — -Z - R Theo gia thiet 9, +(p = — nen ta c6: cot(p, =tan(p =>^=^^-^R^=z,(z,-zJ Vdy chqn dap an B Cdu 10: Hat nhan ^^X ph6ng xa bien mot hat nhan ^^^Y ben Coi khoi lifcfng cua hat nhan X , Y bang so khoi cua chung tinh theo dcfn v i u Biet chat phong xa X c6 chu k i bdn 1^ T Ban dau c6 mot khoi lifcfng chat ^^X, sau chu Id ban t h i t i so giffa khoi Iffdng cua chat Y A - ^ Aj khoi lUcfng cua chat X la: B ^ A, C ^ A, Sau chu kX, so hat nh^n X c6n lai 1^: D = T i so' kho'i Ifftfng cha't Y • • X la: = 3^ Aj = So hat nhan cua chat Y hinh th^nh la: N„ = N * Vdy chon dap an B N^A, ^ = -N^ = 3^ A, ^ G i i c h i l i S t ( J « t h i T S B H , C D M n V$t« Cdu 11: M o t v a t dao dong dieu hoa c6 chu k i l a T N e u chon goc thcfi gian t = l a luc v a t qua v i t r i can bang, t h i t r o n g nufa chu k i dau t i e n , van toe cua v a t b k n g k h o n g of t h d i diem: T A t = - B.t=I C.t= T - D I Giai Chon goc t h d i gian t = l a luc v a t qua v i t r i can b k n g , t h i — chu k i nufa v a t se tcri b i e n v a v a n toe b k n g k h o n g T r o n g nufa chu k i dau T tien, v a n toe cua v a t b k n g k h o n g d thdi diem t = — Vdy chon dap an B Cdu 12: M o t l a t h e p mong, m o t dau co d i n h , dau l a i diJtfc k i c h t h i c h de dao dong v d i chu I d k h o n g doi va b k n g 0,08 s A m l a t h p phat r a l a : A sieu a m B am C nhac a m D a m m a t a i ngifdi nghe diftfc Giai T a n so a n t h e p p h a t r a : f = - = — ^ = 12,5 < 16Hz T 0,08 T a i ngifori k h o n g t h e nghe di/grc a m co t a n so dtfdi 16Hz n e n a m la thep p h a t r a l a h a a m Vdy chon dap an B Cdu 13: P h a t bieu nao sau day l a s a i k h i n i ve p h o n g x a (hoat d6 phong xa)? A Dcfn v i do phong xa l a beccfren B Do phong xa l a d a i luang dac trifng eho t i n h p h o n g xa m a n h hay yeu cua m o t li/cfng chat phong xa C Vdri m o i iLfotng chat phong x a xAc d i n h t h i dp p h o n g x a t i le vdri so nguyen tuf cua liTcfng chat D E)o phong xa cua m o t lacfng chat ph6ng xa p h y thuoc n h i $ t dp cua lUtfng chat Giai Do phong x a cua m o t li/tfng chat phong x a k h o n g p h u thuoc v k o cdc tac dong b e n ngoai nhtf n h i e t do, ap suat, a n h sang, Vdy chon dap an D GIJichitiStdlthiTSDH, CDMdn V l L t l f Cdu 14: Doan mach dien xoay chieu khong phan nhanh gom a/^n day C O tir cam L , dien t r d thuan R va tu dien c6 dien dung C K h i dong dien c6 tan so' goc chay qua doan mach t h i he so cong suat cua doan mach A bang B phu thuoc dien trof thuan cua doan mach C b k n g l D phu thuoc tong irb cua doan mach GiSi K h i dong dien c6 tan so goc chay qua doan mach t h i xay hi^n tiTtfng cong hLfomg K h i u, i cung pha va he so cong suat cua doan mach bang Vdy chgn dap an C Cdu 15: Cho hai dao dong dieu hoa cung phiTcfng, cung tan so, cung bien va c6 cac pha ban dau la — va - — Pha ban dau cua dao dong tong hcfp hai dao dong tren bkng: A ^ 12 B ^ C D ^ Giai Pha ban dau cua dao d6ng tong hap hai dao dong tren bang 7t 12 Vdy chgn dap an A Cdu 16: Trong mot mach dao dong LC khon^ c6 dien t r d thuan, c6 dao dpng dien tii ttf (dao dong rieng) Hieu dien the CLTC dai gifla hai ban tu va ctr&ng dong dien ciJc dai qua mach Ian Itfcft la Uo va I Q T Tai thdi diem ctfofng dong dien mach c6 gia t r i y t h i 16n hieu dien the giiJa hai ban tu dien la: A ^ U o C.iu, B |Uo D ^ U , Gi^i Chi ti^t de thi T S B H , C D IVIon Vat If Giai cu nen W = Wd + Wt O Wt = W - Wa cu' LI' LI' 8 Vay chgn dap an D Cdu 17: Trong quang cua nguyen tuf hidro, neu biet h\idc song dai nhat cua vach quang day Laiman la X, i va h\i6c song cua vach ke vdfi no day la ^2 thi h\idc song cua vach quang day Banme l a : A (X,-^,)- c B + D Giai Difa vac scf chuyen mufc nSng Iifpng, ta c6: hfi = E i - E o (1) hf2 = E2 - Ee (2) hf„ = E2 - E l (3) E3- E2- K Ei- TrCf ve vdi ve (2) va (1) ta difpc: Eo- hf„ = hf2 - hfi 1-v he ^ he he V i hf = — nen — = he =>^„ = Vay chgn dap an B Cdu 18: Phat bieu nao sau day l a s a i k h i noi ve dao dong cua iSc dcfn (bo qua liic can cua moi triTdng)? A Vdri dao dong nho thi dao dong cua lac l a dao dong dieu h6a B K h i vat nang d vi tri bien, cd nang cua lac bang the nang cua n6 C Chuyen dong cua iSc tCf vi tri bien ve vi tri can bang la nhanh dan D K h i vat nang di qua vi tri can bang, thi ILTC tac dung len no can Vlng vdi life cSng cua day Giai Chi l e t d6 thi TS DH, CD Mdn V$t If Cdu 17: X e t diem M cf t r o n g m o i trifcfng dan h o i c6 song a m t r u y e n qua Mijfc cirdrng a m t a i M la L (dB) Neu ci/cfng a m t a i d i e m M tang l e n 100 I a n t h i mufc cifcfng a m t a i d i e m b a n g A IDOL (dB) B L + 100 (dB) C 20L (dB) D L + 20 (dB) Giai Luc dau L = l O l g — K h i t a n g ctfomg a m I ' = 1001 t h i : ^0 L' = l O l g — = l O l g — + lOlglO^ = L + 20 (dB) ^0 ^0 Vdy chon dap an D Cdu 18: K h i n o i ve a n h sang, p h a t bieu nao sau day s a i ? A A n h sang t r a n g la h n hgfp cua nhieu a n h sang don sac c6 mau bien t h i e n l i e n tuc iii den t i m B A n h sang don sac k h o n g b i t a n sac k h i d i qua l a n g k i n h C Chiet suat cua chat l a m l a n g k i n h doi vdri cac a n h sang don sac khac deu bang D Chiet suat cua chat l a m l a n g k i n h doi vdri cac a n h sang dcfn sac khac t h i khac GiSi Chiet suat cua chat l a m l a n g k i n h doi vcfi cac a n h sang dom sac khac t h i khac nhau, vay dap a n C la p h a t bieu sai Cdu 19: D a t dien ap u = u V cos27tft ( t r o n g U k h o n g doi, f t h a y doi di/Oc) vao h a i dau dien t r d t h u a n K h i f = f i t h i cong suat t i e u t h u t r e n dien t r d b a n g P K h i f = f2 v i £2 = f i t h i cong sua't t i e u t h u t r e n dien t r d bang A V P B - CP D 2P Giai CiTcfng dong dien qua d i e n t r d t h u a n k h o n g p h n chuoc vao t a n so f Do P k h o n g doi Vdy chgn dap an C Cdu 20: H a i v a t dao dong dieu hoa doc theo cac true song song v d i Phifcfng t r i n h dao dong cua cac v a t I a n \\Jat la x i = Aicoscot (cm) va X2 = Aasincot (cm) B i e t 64 + 36Xj = 48^ (cm^) T a i thcfi d i e m t , vat thuf n h a t d i qua v i t r i c6 l i x i = 3cm vdri v a n toe v i = - cm/s K h i v a t thuf h a i c6 toe bang A 24 V3 cm/s B 24 cm/s Giai Chi ti^t (3« thi TS BH, CB M6n Vat li C cm/s D 8V3cm/s 79 TOf 64 (x'l = v i ; x'2 GiSi + 36 X2 = 48^ (cm^), lay dao ham hai ve theo thdri gian t = V2) Ta c6: 128xiVi + 72x2V2 = Khi xi = Aicoscot = (cm) t h i V i = -coAisincot = - (cm/s) Suy ra: 36x2^ = 48' - 64.3' = 1728 =^ xg' = 48 => xa = ± V3 (cm) TCr 128xivi + 72x2V2 = Suy ra: vg = Khi vat thuT x i V i + 9x2V2 =•• = ± 8V3 (cm/s) hai c6 t o e bang Vs (cm/s) Vay chgn dap an D Cdu 21: Tai mot v i t r i tren Trai Dat, lac don c6 chieu dai i^ dao dong dieu hoa v6i chu k i T i ; lac dan c6 chieu dai ^, ( f , < ^1) dao dong dieu hoa chieu dai ^, A vdri chu k i T2 Cung tai v i t r i do, lac dan c6 dong dieu hoa -11^ B vdri TTM? chu k i la D C VT,'+T,^ Giai Ap dung cong thiJc: T = 2;: j - =^ I = ^ =^ Vg 4% • Suy ra: V = l , - l , ^ ^ = ^^^[ 471 ^ = 4n I2 = ^ An ^Tp^ T = 47t Vay chgn dap an B Cdu 22: K h i mot vait dao dong dieu hoa, chuyen dong cua vat tii vi t r i bien ve v i t r i can bang la chuyen dong D cham dan C nhanh dan B cham dan deu A nhanh dan deu G\k\ Khi vat dao dong dieu hoa, tCif v i t r i bien ve v i t r i can bang la chuyen dong nhanh dan Vay chgn dap an C Cdu 23: Dat dien ap xoay chieu vao hai dau doan mach X mac noi tiep chufa hai ba phan tuf: dien t r d thuan, cuon cam thuan va tu 80 Q\k\i tiet de thi TS DH, CD Mon Vat li dien B i e t r k n g dien ap giufa h a i dau doan m a c h X l u o n s6m pha so vdi cJcfng dong dien t r o n g mach mot goc nho hofn Doan mach X chufa A cuon cam t h u a n va t u dien vdri cam k h a n g \6n hern dung k h a n g B dien tror t h u a n va t u dien C cuon cam t h u a n va t u dien v d i cam k h a n g nho h a n dung k h a n g D d i ^ n tror t h u a n va cuon cam t h u a n Giai Ta CO < < ^ Mach C O t i n h cam k h a n g , doan mach X chufa R va L Vay chon dap an D Cdu 24: T a i m a t thoang cua m o t chat l o n g c6 h a i nguon song S i va S2 dao dong theo phucfng t h a n g dufng v d i cung phtfcfng t r i n h u = acos407it (a k h o n g ddi, t t i n h bang s) Toe t r u y e n song t r e n m a t chat long bang 80 cm/s Khoang each ngfin n h a t giufa h a i p h a n tuf chat long t r e n doan t h i n g S1S2 dao dong v d i b i e n ciic d a i l a A cm B cm C cm D cm Giai V Bifde song X = — = A cm Khoang each ngSn n h a t giCJa h a i p h a n tuf chat l o n g t r e n doan X, t h i n g 8182 dao dong v d i b i e n ciic d a i la la d = — = cm Vay chon dap an C Cdu 25: H a i h a t n h a n va ^He c6 cung A so noftron B so' nuclon C di&n t i c h Giai H a i h a t n h a n ]l D so p r o t o n va 2He eo cung so nuclon l a Vay chon dap an B Cdu 26; M o t song ngang t r u y e n t r e n scfi day r a t d a i v d i toe truyen song la 4m/s va t a n so song c6 gia t r i tCf 33 Hz den 43 H z B i e t hai phan tuf t a i h a i d i e m t r e n day each 25 cm luon dao dong ngiioc pha T a n so song t r e n day la A 42 Hz B 35 Hz C 40 H z D 37 H z Giai Khoang each giufa h a i d i e m dao dong ngiTcfc pha l a : Giai Chi tid't de thi T S DH, C D M6n VSt 11 181 d = l k + - 2j l k+- V Suy r a : f = 2) V f k l d Suy r a : 33 < f = 16k + < 43 Vdy chgn dap an C 0,25 = 16k + • k = va f = 40Hz Cdu 27: M o t mach dao dong l i tufdng dang c6 dao dong dien tii tif vdri chu k i dao dong T T a i thcfi diem t = 0, dien t i c h t r e n mot ban tu dien dat gia t r i ciic d a i D i e n t i c h t r e n b a n t u bang d thcfi d i e m dau t i e n (ke tCf t = 0) la T A I B.I D.I C 2% Tt k 2K Ta c6: q = QQCOS — t = T.t — = — + k t = > 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[...]... Tang tach song chi c6 or may thu Vdy chgn dap an C Giai Chi tigt (JS thi T S B H , C B M6n V*t l( 26 DE THI TUYEN SINH DAI HQC NAM 2009 Mon thi: VAT L I - K h o i : A Thdl gian lam bai: 90 phut Cdu 1: Dat dien ap u = Uocoscot vao hai dau doan mach mac noi tiep gom dien trd thuan R , tu dien va cuon cam thuan c6 do tiX cam L thay doi diftfc Biet dung khang cua tu dien bang R V S Dieu chinh L de dien... h o n g B Chi C O dong dien xoay chieu ba pha m d i tao diic/c tCf tn/c/ng quay C K h i ciidng do dong dien t r o n g m o t pha ctfc d a i t h i ci/cfng do dong dien t r o n g h a i pha con l a i ctfc tieu D Dong dien xoay chieu ba pha la h e t h o n g gom ba dong dien xoay chieu m o t pha, lech pha nhau goc 2n — Giai Dong dien xoay chieu ba pha la he t h o n g gom ba dong d i e n xoay chieu m o t... thich, thay ddi k i m loai lam catot thi dong nang ban dau ciTc dai cua electron (electron) quang dien thay doi C Giuf nguyen t a n so cua anh sang kich thich va kim loai lam catot, tang cifcfng do chum sang kich thich t h i dong nang ban dau c\Xc dai cua electron (electron) quang dien tSng D Giu" nguyen ctfcfng do chum sang kich thich va kim loai dung lam catot, giam hiidc song cua anh sang kich thich... Gt&i Chi ti^t d l thi TS OH CD M6n V$t II I 17 Khi do dao dong tai O sdm pha hon tai M la 27rd Phi/ong t r i n h dao dong cua phan tuf vat chat tai O la: Uo(t) = asin27r Vdy chqn dap an C Cdu 38: K h i c6 hien ttfcrng quang dien xay ra trong te bao quang dien, ph6t bieu nao sau day la sai? A Giuf nguyen cLforng do chum sAng kich thich va k i m loai dung lam catot, giam tan so cua anh sang kich thich... t suat cua m o t m o i tri/ofng t r o n g suot doi v6i d n h sdng d6 \&ti hon chiet suat cua m o i t n i d n g do doi vdri a n h sang t i m Doi v d i a n h sdng dcfn s^c, chiet suat cua m o t m o i triTdng t r o n g su6't doi vdri a n h sang tSng len tiif do den t i m V i vay chiet suat cua d n h sdng do p h a i nho hcfn chiet suat cua m o i triicfng do d6'i v d i a n h sang t i m Vay chgn dap an... Vdy chgn dap an D 12 Giai Chi ti^t dS thi T S DH, C D M6n V^t If Cdu 27: T r o n g t h i n g h i e m giao thoa a n h sang vdfi khe l a n g (Y-ang), khoang each giffa h a i khe la 2 m m , khoang each tii m a t p h a n g chufa hai khe den m a n quan sat la 1,2 m Chieu sang h a i khe b a n g a n h sang hon hop gom h a i a n h sang dcfn sSc c6 badfc song 500 n m va 660 n m thi thu diXac h§ v a n giao... o t tha'u k i n h m o n g bang t h u y t i n h h a i m a t cau l o i , c6 chiet suat tuyet doi n T h a u k i n h nay c6 do t u : A a m k h i d a t t r o n g m o i triicfng c6 chiet suat tuyet doi n ' < n B difcfng k h i dat t r o n g m o i trUofng c6 chiet suat tuyet doi n ' = n C a m k h i dat t r o n g m o i tri/ofng c6 chiet sua't tuyet doi n ' > n D luon dUtfng, k h o n g phu thuoc vao m o... mach c6 bieu thiJc l a i = l-Jlcos 4 ( A ) Cong sua't tieu t h u cua doan mach n a y l a : A 2 2 0 V 2 W B 440W C 4 4 0 V 2 W D 220 W G\k\ Dp lech pha giuTa ciTdng do dong di^rt v a h i e u dien t h e : V2 ^2 n ^ 4 14 Giai chi. tigf 66 thi TS DH, CD M6n VHt II Cong suat t i e u t i i u cua doan mach: P = U I cos 2 = 0,6m V a n toe t r u y e n song: v = >uf = 0,6.100 = 60m/s Vay chon Giai Chi tiSt dap an C thi T S D H , C D M 6 n V $ t li ' 29 Cdu 5: Chieu x i e n m o t chum sang hep gom h a i a n h sang dotn sac la v a n g va l a m tCf k h o n g k h i t d... Giai Chi tietde thi TS D H , C D Mon Vat li , ' 19 Cdu 42: Mach dao dong cua mAy thu song v6 tuyen c6 tu dien v