If the centripetal and thus frictional force between the tires and the roadbed of a car moving in a circular
path were reduced, what would happen?

In this particular case, where car is moving through curvature, so it is moving in circular motion, force acting on car is centripetal force which holds car not to fly out. Centripetal force is always pointed in the middle of circle. Here frictional force has role of centripetal force. If frictional force is to weak, car would fly out of curvutare.

It indicates no change in temperature and the process of matter changing its state