The co-ordinates of a moving particle at any time '$t$' are given by $x = \alpha t^{3}$ and $y = \beta t^{3}$. The speed of the particle at time '$t$' is given by
(1) $3t\sqrt{\alpha^{2} + \beta^{2}}$
(2) $3t^{2}\sqrt{\alpha^{2} + \beta^{2}}$
(3) $t^{2}\sqrt{\alpha^{2} + \beta^{2}}$
(4) $\sqrt{\alpha^{2} + \beta^{2}}$