当t=2s时,O==0.2×2=04rads 则v=Ra=04×04=0.16 R (04)2=0.06 a2=RB=04×0.2=008m·s2解：当 t = 2 s 时，  = t = 0.2 2 = 0.4 1 rad s −  则 v = R = 0.40.4 = 0.16 1 m s −  0.4 (0.4) 0.064 2 2 an = R =  = 2 m s −  a = R = 0.40.2 = 0.08 2 m s −  2 2 2 2 2 (0.064) (0.08) 0.102 m s − = + = + =  a an a