大学 物理 瞬时速率： △产 d时 v= lim Instantaneous velocity: △t→0 △t dt Notes: ①平均速率：乊= △S △ △t △t ds dr 瞬时速率：v= dt dt = 2In curvilinear motion,the velocity vector is tangential to the curve.瞬时速率： Instantaneous velocity： 0 lim t r v t  →  =  dS v dt 瞬时速率： = ①平均速率： S v t  =  ②In curvilinear motion, the velocity vector is tangential to the curve. Notes: dr dt = r t    = v dr dt = = v 10 大学 物理