Friction on an Inclined Plane: Kinetic or Static?

[stakar11]

Homework Statement

Does kinetic friction and static friction act upon a car traveling downhill (without acceleration by the car)?

Homework Equations

The Attempt at a Solution

Is it kinetic because the wheels rub against the surface and the car is in motion? But is it also static because the wheels are rolling downhill and at each point in time the wheels are stationary in their contact with the ground?

 

[Doc Al]

It's one or the other, but not both. If the tires slip against the surface, it's kinetic friction; if the tires roll without slipping, it will be static friction.

 

[stakar11]

Thanks, that helped a lot!