I. Vocabulary and structure 1. On my way to school, I saw people _advertisements and sample products. A. conveying B.creating C. discarding D. distributing 2. The professor thought that I was making good progress in my studies and told me to my good work A. keep up B. go ahead with C. hold back D. come up with
Lecture D32: Damped Free Vibration Spring-Dashpot-Mass System k Spring Force Fs =-kx, k>0 Dashpot Fd =-cx, c>0 Newton's Second Law (mx =EF) mx +cx+kx (Define)Natural Frequency wn=k/m,and
Lecture D33: Forced Vibration Fosinwt m Spring Force Fs =-kx, k>0 Dashpot Fd =-ci, c>0 Forcing Fext Fo sin wt Newton's Second Law (mix =CF) mx+cx+kx= Fo sin wt =k/m,=c/(2mwn)