A car weighing 2,700 lb (about 1.35 tons) moves along the elliptic path 900x^2 + 400y^2 = 1. If the car travels at a constant speed of 45 mph, how much frictional force is required to keep it from skidding as it turns the "corner" at (1/30,0)? What about the corner (0,1/2)?