Hướng dẫn giải chi tiết đề thi tuyển sinh đại học, cao đẳng môn vật lí phần 2 tờ số (24)

K h o a n g thcfi g i a n diigrc b i e u d i l n b d i h i n h v e : T T 2T t =—+ —= — 3 Vdy chgn dap an B 3: L a z e A p h a t r a c h u m bufc x a c6 bifdc s o n g 0,45 |J.m v d i c o n g Cau suat , W L a z e B p h a t r a c h u m bufc x a c6 bifdc s o n g 0,60 f^m v d i c o n g suat , W T i so giOfa so p h o t o n c u a laze B v a so p h o t o n c u a laze A phat r a m o i giay l a : A 20 B C Giai Taco: n " he T h e o de b a i : ' he = P^l^ 'A _ Vdy chgn dap an A Cau 4: T r o n g t h i n g h i e m Y - a n g v e g i a o t h o a a n h s a n g , n g u o n s a n g p h a t r a a n h s a n g d o n she, c6 biTdc s o n g A , T r e n m a n q u a n s a t , t r e n d o a n t h S n g M N d a i m m ( M N v u o n g goc v d i h e v a n g i a o t h o a ) c6 10 van t o i , M va N l a v i t r i cua h a i v a n sang T h a y a n h sang t r e n b a n g a n h s a n g d o n sac c6 bLfdc s o n g X,, = t h i t a i M l a v i t r i cua m o t v a n giao t h o a , so v a n s a n g t r e n d o a n M N l i i c n a y l a : A B C D Giai K h i t h a y X, t h i so v a n t o i t r e n d o a n M N l a : 5X, 10?ti - k X , = k - ^ k = N g h i a l a c6 v a n s a n g Vay t t o n dap an A Q\h.\i tilt thi T S D H , C D Mon VSt 11 153 Cdu 5: Phong xa va p h a n hach h a t n h a n A deu la p h a n ufng h a t n h a n toa n a n g liicfng B deu la p h a n ufng h a t n h a n t h u n a n g Itfo'ng C deu la p h a n ufng t o n g hgfp h a t n h a n D deu k h o n g p h a i la p h a n ufng h a t n h a n Giai Phong xa va p h a n hach h a t n h a n deu la p h a n ufng h a t n h a n toa nSng \\i(ing Vay chgn dap an A Cdu 6: T a i ncfi c6 gia toe t r o n g trirorng la g, m o t He 16 xo treo t h a n g dufng dang dao dong deu h6a B i e t t a i v i t r i can bang ciia vat dan cua 16 xo la Al Chu k i dao dong cua lac l a : A 271 'A/ B 2K' IT c [7 ^ 27r V A / Giai K h i can bang: m g = k A / Suy r a : T = 271, A/ V g Vdy chgn dap an D Cdu 7: D a t d i e n ap u = UoCoslOOTtt (V) vao h a i dau doan mach A B gom h a i doan mach A M va M B mkc n o i t i e p Doan mach A M gom dien tror t h u a n lOoVsQ m^c n o i tiep vdri cuon cam t h u a n c6 t i f cam L -4 Doan mach M B chi c6 t u dien c6 dien dung ^ - ^ F B i e t dien ap gifla 271 h a i dau doan mach A M lech pha y so vdfi dien ap giufa h a i dau doan mach A B Gia t r i cua L bang A.iH B.iH 71 C D ^ H -'-H 71 It 71 Giai T a co: = 200Q k h i -300Q L = 71 Z , = 100Q L = -H, Z, = L = -H, n 200Q 154 Giai Chi tiSt de thi T S DH, C D M6n Vat li L = — H , ZL =100V2Q Dung phifcfng phap loai triT chon L = — H , = lOOQ 71 Vay chgn dap an C Cau 8: Theo thuyet Itfcfng tuf a n h sang, phat bieu nao sau day l a s a i ? A T r o n g chan k h o n g , ph o t o n bay v d i toe c = 3.10^ m/s doc theo cac t i a sang B P h o t o n cua cac a n h sang dcfn sSc khac t h i m a n g n a n g liTcfng khac C N a n g Itfo'ng cua m o t p h o t o n k h o n g d o i k h i t r u y e n t r o n g chan k h o n g D P h o t o n t o n t a i t r o n g ca t r a n g t h a i diJng y e n v a t r a n g t h a i chuyen d o n g Giai Chon dap an D P h o t o n t o n t a i t r o n g ca t r a n g t h a i dufng y e n va trang t h a i chuyen dong CAu 9: M o t mach dao dong d i e n tCf l i tiJorng dang c6 dao dong d i e n ttf t u Bie't d i e n t i c h ciic d a i t r e n m o t b a n t u d i e n l a ciiofng dong d i e n CLTC |aC va d a i t r o n g mach l a 0,5 kyfl A Thofi g i a n ng&n nhat de dien t i c h t r e n m o t b a n t u g i a m tii gia t r i cifc d a i d e n nufa gia tri CLTC dai la A - a s B — u s ^ C - u s 3^ D - u s Giai T a c o : (o = - ^ = - ' ' r a d / s qo Thcfi gian n g ^ n n h a t de d i e n t i c h t r e n m o t b a n t u g i a m tCf gia t r i X 16 cifc d a i den nufa gia t r i cifc d a i l a : t = — = — 10~^(s) = — |j.s 6 Vdy chon dap an D Cau 10: T r o n g h i e n tMng giao thoa song n\J6c, h a i nguon dao dong theo phiTofng vuong goc vdri m a t nvCdc, cung b i e n do, cung pha, cung t a n so 50 Hz difoTc d a t t a i h a i d i e m S i va S each 10cm Toe t r u y e n song t r e n m a t ni/dfc l a 75 cm/s X e t cac d i e m t r e n m a t ntrdrc thuoc di/orng t r o n t a m S i , b a n k i n h S1S2, d i e m m a p h a n tijf t a i dao dong vdfi bien CLTC A 85 m m d a i each d i e m S2 m o t doan n ga n n h a t b k n g B 15 m m Giai Chi tiSt 66 thi T S D H , C D M o n V a t II C 10 m m D 89 m m 155 ... H -'-H 71 It 71 Giai T a co: = 20 0Q k h i -300Q L = 71 Z , = 100Q L = -H, Z, = L = -H, n 20 0Q 154 Giai Chi tiSt de thi T S DH, C D M6n Vat li L = — H , ZL =100V2Q Dung phifcfng phap loai triT... vat dan cua 16 xo la Al Chu k i dao dong cua lac l a : A 27 1 'A/ B 2K' IT c [7 ^ 27 r V A / Giai K h i can bang: m g = k A / Suy r a : T = 27 1, A/ V g Vdy chgn dap an D Cdu 7: D a t d i e n ap u... , b a n k i n h S1S2, d i e m m a p h a n tijf t a i dao dong vdfi bien CLTC A 85 m m d a i each d i e m S2 m o t doan n ga n n h a t b k n g B 15 m m Giai Chi tiSt 66 thi T S D H , C D M