* Acceleration is a vector: Acceleration has both magnitude (how fast the velocity is changing) and direction.
* Turning implies a change in direction: When a car turns right, its velocity vector changes direction, even if its speed remains constant.
* Change in direction means acceleration: Since acceleration is the rate of change of velocity, a change in the direction of velocity implies acceleration.
In other words:
Even if the car is maintaining a constant speed while turning, the change in direction means that the car is experiencing centripetal acceleration. This acceleration is directed towards the center of the curve the car is making.
