(3)=4-6t2=4-6×12=-2m/s Ln=4-6t2=4-6×32=-50m/s L-1h1-50-(2) t2- t 3-1 24m/s2 d C =-12t=-12×3 dt 36ms2 结束目录3 6 2 v = 4 t = 4 6×32 = 50 m s 2 = 24 m s = 12 ×3 2 = 36 m s 1 6 2 v = 4 t = 4 6×12 (3) = 2 m s 12 t a = dv = d (4) t v1 ( ) v3 t 3 t 1 a = = 50 2 3 1 结束 目录