Cdu 5: C h a t p h o n g x a p o l o n i g°Po phat t i a a va bien doi t h a n h c h i ^s'Pb C h o c h u k i b a n r a cua '^°Po l a 138 n g a y B a n d a u ( t = 0) c6 m o t m a u p o l o n i n g u y e n c h a t T a i thofi d i e m t i , t i so giuTa so h a t n h a n p o l o n i v a so h a t n h a n c h i t r o n g mku la T a i thcfi d i e m t2 = t i + 276 n g a y , t i so giufa so h a t n h a n p o l o n i v a so h a t n h a n c h i t r o n g m l u l a A 25' B 16 C i D _1_ 15 Giai 93,75% 6,25% 1:7 87,5% 12,5% 1:3 75% 25% 1:1 50% 50% AN, No No AN, N, t n = — T D i i a v a c b a n g suy r a t i = T = n g a y v a t i n h la N, 1:15 = T V a y t i le c a n 1:15 Vay chgn Cdu dap an D 6: M o t c h a t d i e m dao d o n g d i e u h o a t r e n t r u e O x K h i c h a t d i e m d i q u a v i t r i c a n b a n g t h i toe cua n o l a 20 c m / s K h i c h a t d i e m c6 t o e l a 10 c m / s t h i g i a t o e cua n o c6 16n l a \ / c m / s ^ B i e n dao d o n g c u a c h a t d i e m l a : A cm B cm C e m D 10 c m Giai Taco: (V,,CBU Khi 2, " = (1) = 20 cm/s ( o ' A = 40V3 cm/s^ thi T h a y (1) v a o (2) s u y r a : co = ( r a d / s ) Vay chgn dap an (2) A = 5cm B t r u e CO d i n h mot 7: M o t k h u n g d a y d f i n p h ^ n g q u a y d e u v d i t o e g6c Cdu nam t r o n g m a t p h d n g k h u n g day, trtforng d i u co veetcf c a m ufng tCf v u o n g goc co quank, t r o n g m o t tiif vdfi t r u e q u a y cua k h u n g 108 Gi4ichiti6t(3SthiTSDM, CDMSnV^tK Suat dien dong cam ufng t r o n g k h u n g c6 bieu thuTc e = Eocos(cot + Tai thori d i e m t = 0, vecto phap tuyen cua m a t p h a n g k h u n g day hop vdi vectof cam ufng tii m o t goc bSng A 150° B 90° C 45° D 180° Giai V i pha ban dau tCf t h o n g n h a n h htfn pha ban dau suat d i e n dong motgoc nen ( ( P o ) ^ = ( ( P o ) _ ^ + ^ = 7r Vdy chon dap an D Cau 8: K h i noi ve mot vat dao dong dieu hoa, phat bieu nao sau day sai? A Ccr n a n g cua v a t bien t h i e n tuan hoan theo t h d i gian B Life keo ve tac dung l e n v a t bien t h i e n dieu hoa theo thofi gian C V a n toe cua v a t b i e n t h i e n dieu hoa theo thcfi gian D Dong n a n g cua v a t bien t h i e n t u a n hoan theo thcfi gian Giai Trong dieu k i e n \i tUo'ng, cd n a n g k h o n g t h a y doi theo thcfi gian; dieu k i e n k h o n g \i tudng, cof nang g i a m d a n theo t h d i gian Vay chgn dap an A Cau 9: M o t doan mach A B gom hai doan mach A M va M B mic noi tiep Doan mach A M gom dien t r d t h u a n R i mac n o i t i e p vdfi t u dien CO dien dung C, doan mach M B gom dien t r d t h u a n R2 mSc n o i tiep vdri cuon cam t h u a n c6 tiX cam L D a t dien ap xoay chieu c6 t a n so va gia t r i hieu dung k h o n g doi vao hai dau doan m a c h A B K h i doan mach A B t i e u t h u cong suat b k n g 120 W va c6 he so cong suat bang Neu n o i t a t h a i dau t u dien t h i dien ap giufa h a i dau doan mach A M va M B c6 cung gia t r i hieu dung nhifng lech pha ^, cong suat tieu t h u t r e n doan mach A B t r o n g tnTdng hcfp bang: A 180 W B 160 W C 90 W D 75 W Giai Taco: coscp^l^P,,^, Giaichi tietde thi T S D H , C D MSn vat If R1+R3 ' = 120W (1) 109 Sau k h i noi t a t t h i m a c h d i e n R i , R2 va L ; M nkm giUa R i va R2 V i UAM = UMB n e n tarn giac A M B can suy r a UAB htfp v6i I mot goc (p = 30° V a y k h i do: P = U COS (p L a y (2) chia cho (1) t a c6: P = cos" (p-P^^, = ^3 (2) 120 = 90W Vay chgn dap an C Cdu 10: T r o n g nguyen tijf h i d r o , b a n k i n h Bo la ro - , " " m mot t r a n g t h a i k i c h t h i c h cua nguyen tijf h i d r o , electron chuyen dong tren quy dao diTng c6 b a n k i n h la r = 2,12.10"^°m Quy dao c6 t e n goi la quy dao dtog: A N B M C O D L Giai A p d u n g cong thufc: r = ron^ => n = J — = Vgy chgn dap IJfng v o l t r a n g t h a i dCrng L an D Cdu 11: B a n m o t p r o t o n vao hat n h a n ! L i dufng y e n P h a n ufng tao hai h a t n h a n X giong bay vo'i cung toe va theo cac phiTOng hcfp vdfi phUo'ng tdi cua p r o t o n cac goc bang la 60° Lay khoi lirgrng cua m i h a t n h a n t i n h theo do'n v i u b a n g so k h o i cua no T i so giuTa toe cua p r o t o n va toe cua h a t n h a n X la A i c i B D Giai Dau h i eu n h a n dang: h a t X(He) c6 dong luong b a n g va htfp m o t goc 120° nen Px - Pp mnoVHe = mpVp Me = Suy r a 'He —p Vgy chgn dap an D 110 Giai Chi tiet de thi TS DH, CD Mon Vat li ... Giai Taco: coscp^l^P,,^, Giaichi tietde thi T S D H , C D MSn vat If R1+R3 ' = 120 W (1) 109 Sau k h i noi t a t t h i m a c h d i e n R i , R2 va L ; M nkm giUa R i va R2 V i UAM = UMB n e n tarn... a UAB htfp v6i I mot goc (p = 30° V a y k h i do: P = U COS (p L a y (2) chia cho (1) t a c6: P = cos" (p-P^^, = ^3 (2) 120 = 90W Vay chgn dap an C Cdu 10: T r o n g nguyen tijf h i d r o , b... a t X(He) c6 dong luong b a n g va htfp m o t goc 120 ° nen Px - Pp mnoVHe = mpVp Me = Suy r a 'He —p Vgy chgn dap an D 110 Giai Chi tiet de thi TS DH, CD Mon Vat li