In a banked curve scenario, the normal force's horizontal component, N*sin(theta), contributes to the centripetal force required for a car to turn. When a car is at rest (v = 0), N*sin(theta) can still be greater than zero due to gravitational forces, but there is no centripetal force acting since mv^2/r equals zero. The design of banked curves considers the expected speed range for vehicles, factoring in static friction to prevent sliding. If the car is stationary, friction must be present to prevent it from sliding down the slope. Understanding these dynamics clarifies the relationship between normal force, friction, and the design of banked curves.