A moving particle has coordinates in millimeter which vary with the time t in seconds according to r=(2t^2-4t)i + (3t^2 -t^3/3)j . where r is in millimeters and t is in seconds.
a- determine the velocity v and acceleration a.
b- determine the magnitude of the velocity v and the angle which the velovity vector makes with the x-axis when t=2 sec.