Thay gia tri tren vao (2) ta c6: X = k X 7x 720 = — ^ = 560nm Vay chgn dap an D Cdu 14: Dung mot proton c6 dong nang 5,45 MeV ban vao hat nhan ' B e dang dufng yen P h a n ufng tao hat nhan X va hat a Hat a bay theo phiTofng vuong goc vdfi phi/cfng tdfi cua proton va c6 dong nang MeV K h i tinh dong nang cua cac*hat, lay khoi liigfng cac hat tinh theo dcfn vi khoi luftfng nguyen tuf bang so khoi cua chiing NSng li/gfng toa phan ufng bang: A 3,125 MeV B 4,225 MeV C 1,145 MeV D 2,125 MeV Giai Hat tao theo phan ufng: JH+ ' B e ^ ^He Sijf dung cac dinh luat bao toan ta c6 Z = 3, A = Nhtf vay, hat X chinh la L i Theo dinh luat bao toan dong liXgfng ta c6: Pp = P„ + P^ Bieu dien cac vector nhir hinh ben TCf hinh ve ta c6: P„^ +P„^ = Py a p X (1) Matkhdc: E m V^ = P; =2m „E„ a a a E P: =2m E„ Thay vao (1) ta difgrc: 2m„E„ +2mpEp = 2m^E^ Tac6:4E + E„=6E.=E.=i5^-M±M5= 6 3,575MeV Nang lircfng toa r a cua phan ufng bkng tong dong nang cua hat a, X trii di dong nang proton: W = + 3,575 - 5,45 = 2,125MeV Vdy chgn Udp an D Cdu 15: Mot mach dao dong li tifdng gom cuon cam thuan c6 tU cam L khong doi va tu dien c6 dien dung C thay doi di/Oc Dieu chinh dien dung cua tu dien den gia tri C i thi tan so dao dong rieng cua mach la fi Giai Chi ti^t 60 thi TS BH, CD Mfin VJt H