A marble starts from rest and moves along a straight line at time [math]t[/math] seconds after passing a fixed point [math]O[/math], with its velocity, [math]v[/math][math]ms^{-1}[/math], given by [math]v=2t^2-6t-6[/math].
(a) Calculate the velocity of the marble, in [math]ms^{^{-1}}[/math] when [math]t=2[/math].
(b) Calculate the acceleration of the marble when [math]v=14ms^{-1}[/math].