[list=1][*]Add a slider and name it [b]t[/b].[br][/*][*]Using the input bar enter: [b]P=(2-4t,-8+8t)[/b]. [br][/*][*]Using the input bar enter: [b]v=(-4,8)[/b][br][/*][*]Select Vector from point (3rd menu) then select [b]P[/b] and [b]v[/b].[br][/*][*]Hide the vector at the origin and the point [b]P’[/b]. [br][/*][*]Using the input bar enter: [b]Speed=Length[v][/b][br][/*][/list]