75. The radius vector of a material point changes with

75. The radius vector of a material point changes with time according to the law r = At2i + Btj, where A = 0,4 m / s2, B = 0,1 m / s; i and j - unit vectors of the coordinate axes x and y. Determine the expression for υ (t) and a (t); Modules speed and acceleration, tangential and normal components of acceleration at time t = 2 s.