革擦大寧 信德博学 求创案 South chi na Agricul tural Uni versity Velocity vector ① average velocity △ 2 instantaneous velocity △ v=lim △1→>0△tdt ·Acce| eration vector ① average acceleration △ 2 instantaneous acceleration △v =im △口→0△tdt 6D e p. p h y sic s D e p. p h y sic s D e p. p h y sic s 6 • Velocity vector ① average velocity ② instantaneous velocity • Acceleration vector ① average acceleration ② instantaneous acceleration r v t      0 lim t r d r v  t dt         v a t      0 lim t v d v a  t dt        