At the instant shown, cars A and B travel at speeds of 30 m/h and 20 mi/h, respectively....

At the instant shown, cars A and B travel at speeds of 30 m/h and 20 mi/h, respectively. If A is increasing its speed at 400 mi/h² whereas the speed of B is decreasing at 800 mi/h², determine the velocity and acceleration of B with respect to A.