Vdy chon dap an A.. vector ciTdng do dien triJdng E va vectcf cam ufng tCr B luon vuong goc vdi phtTcfng truyen song.
Trang 1DE THI TUYEN SINH DAI HQC, CAO DANG NAM 2008
MonthI: V A T L I - K h o i A Thdi gian lam bai: 90 phut
Cdu 1: K h i chieu Ian liftft hai buTc xa c6 t a n so la f^, iz (vdi fi < £3) vko
mot qua cau k i m loai dSt c6 lap t h i deu xay r a h i | n ttfcfng quang dien
vdi dien the cifc dai cua qua cau Ian lufdt la V i , V2 Neu chieu dong t h d i
hai bufc xa t r e n v^o qua cau nay t h i dien the cifc dai cua no \k:
A. V2. B. (Vi + V2). C. Vi D, IVi - V2I
Giai
V i fi < f2 nen V2 > Vi
Neu chieu dong t h d i hai bufc xa t r e n v^o qua cau t h i di$n the cifc
dai cua no chi hang dien the Idn hcfn, do chinh la V2
Vdy chon dap an A
Cdu 2: Trong t h i nghiem ve song dCrn^, t r e n mot stfi day dan h 6 i d^i
1,2 m vdi hai dau co dinh, ngUdi ta quan sat thay ngoai h a i dau day co
dinh con co h a i diem khac t r e n day khong dao dong B i e t k h o a n g t h d i
gian giOfa hai Ian l i e n tiep sgti day duoi t h i n g la 0,05 s V a n toe truyen
song t r e n day l a :
A 16 m/s B 4 m/s C 12 m/s D g m/s
Giai
Theo de bai t h i t r e n day tao t h a n h 3 m u i song, m o i m i i i s6ng co
chieu dai —
2
T a c o : 3 - = 1,2 = > = 0,8m
2
Khoang t h d i gian giffa hai Ian l i e n tiep stfi day a j 6 j t h i n g la 0,05s
nen ta co chu k i T = 0,05.2 = 0,1s
5i, 0 8 Van toe truyen song t r e n day: ^ = ^ ~ " Q T ~ ^ C ™ ' ^ ) '
Vdy chon dap an D
Cdu 3: Doi v d i SLT Ian truyen song dien tCf t h i
A vector ciTdng do dien triJdng E va vectcf cam ufng tCr B luon
vuong goc vdi phtTcfng truyen song
Giai Chi tiSt (3e thi TS DH, CO M6n vat li 3