Final answer:
A car driving around a curve at constant speed is experiencing uniform circular motion, which involves centripetal acceleration and force, crucially provided by the friction between the tires and road.
Step-by-step explanation:
A car driving at a steady speed around a curve is an example of uniform circular motion. This type of motion involves a constant speed, but the direction of velocity is continually changing. As a result, the car is accelerating towards the center of the circle due to what we term centripetal acceleration. This acceleration arises from the centripetal force, which is responsible for changing the direction of the vehicle's motion.
The forces involved in this motion include the friction between the tires and the road, providing the necessary centripetal force to keep the car from skidding outwards. Without this friction, the car would not be able to follow the curve and would continue moving in a straight line as dictated by Newton's first law of motion. The design of the curve, such as a banked track, can also contribute to the centripetal force, reducing the reliance on friction alone. Newton's third law explains that while the car exerts a force on the road, the road exerts an equal and opposite force on the car, which allows it to navigate the turn.
When a car moves through an ideally banked curve, no lateral force is felt by the passengers since the normal force from the car seat (acting at the banked angle) provides the necessary centripetal force. If a mass is moving around a circle on a frictionless surface and is attached to a nail by a string, the tension in the string provides the centripetal force, analogous to the role of friction in the case of the car on the road.