At a certain time instant, the vector → a ( t ) a→(t) has → a = − ^ ı + 4 ^ ȷ m ˙ → a = ^ ı + ^ ȷ m / s . a→=−ı^+4ȷ^ ma→˙=ı^+ȷ^ m/s. matlab/mathematica input: avec = [-1,4] adotvec = [1,1] at this same instant of time, what is d d t ∥ proj ( → a ( t ) , ^ a ( t ) ) ∥ ddt‖proj⁡(a→(t),a^(t))‖?