The curves on a race track are banked to make it easier for cars to go around the curves at high speed. Draw a free-body diagram of a car on a banked curve. From the motion diagram, find the direction of the acceleration.

The acceleration is directed toward the center of the track.
The acceleration is in the direction the car is moving.
The acceleration is directed outward from the center of the track.

(a) What exerts the force in the direction of the acceleration?

(b) Can you have such a force without friction? (Explain.)

a. friction from the road

b. no, it would be like driveing on ice.

(a) You could say the forces exerted by the tires of the car on the track are responsible for the force in the direction of the acceleration. Or, as I like to call them, the "rubber road grips."

(b) No, you can't have such a force without friction. Friction between the tires of the car and the surface of the track is what provides the necessary force for the car to accelerate in the desired direction. Without friction, the car would just slide off the track like a clumsy penguin trying to ice skate.

(a) The force in the direction of the acceleration is exerted by the friction between the tires of the car and the surface of the track.

(b) No, such a force cannot exist without friction. Friction provides the necessary centripetal force that allows the car to stay on the curve and undergo circular motion. Without friction, the car would continue in a straight line and would not be able to navigate the curve.

(a) The force that exerts the acceleration in the direction of the car's motion is the frictional force between the tires of the car and the road surface.

(b) No, the force in the direction of acceleration cannot exist without friction. In order for the car to maintain its motion along the curved path, a centripetal force is required. Friction between the tires and the road surface provides this centripetal force, allowing the car to safely navigate the curved track. Without friction, there would be no force to keep the car on the curved path, and it would slide off tangentially to the curve.