A car drives on a curved road that goes down a hill. The car's position is defined by the position vector, r=(-30.0cos(pi/10.0t)]i+[30.0sin(pi/10.0t)]jâ-(Azt)k} ft where Az=7.00ft/s. The image below shows the system projected onto the x-y plane. What is the magnitude, v, of the car's velocity, v, at t = 8.00s?