Uniform Circular Motion - Centripetal Force

[frog0101]

Hi,
For an object moving in uniform circular motion, the centripetal force is given as the sum of all forces acting on this object. However, does this refer to only those forces that act in the horizontal direction, or any which have a horizontal component, or all forces? Since only forces that act horizontally contribute (eg. if a car is moving on flat road, the normal force is not responsible for moving the car in circular motion, but instead the friction is), wouldn't it make more sense for it to be defined as the forces that have a horizontal component?

Thanks

[Bri MT]

The weight force should be cancelling out the normal force

You can also have vertical circular motion