其实你2,3式联立干吗?由2得到
kSv^2 -mg = mdv /dt
所以
mdv/(kSv^2-mg) = dt ------×
kSv^2-mg = kS(v^2-mg/kS) = kS(v-根号mg/kS) (v+根号mg/kS)
mdv/(kSv^2-mg)
= dv m/kS * [1/(v-根号mg/kS) - 1/(v+根号mg/kS)] /2根号(mg/kS) 搞过竞赛,这点不难吧?
×式左右分别积分得到
m/2根号(mg/kS) ln(v-根号mg/kS)/(v+根号mg/kS) = t +C, 其中C为任意常数
[v-根号mg/kS)]/[(v+根号mg/kS ] = ce^t