# Circular motion

1. Mar 29, 2005

### AllSeeing

G'day everyone!
This is my first post here, so hello to everyone.
Anyway, I'm having some trouble with my physics (yr12 in Australia, which is final year high school).

What are the forces acting on a bike that is banking as it travels on a circular road? Is the frictional force exerted on the tires towards the centre of the circle equal to the net centripedal force towards the centre of the circle?

Thanks greatly for any help!
Daniel

2. Mar 29, 2005

### whozum

Welcome.

Draw a force diagram and identify the forces at work. There are two forces, gravity and friction. On a level surface, what is pulling the bike towards the center of the circle? Friction or gravity? A combination?

You know the friction force has magnitude $$mu_s mg$$, what effect does banking the bike have on the direction of the friction force?

These questions should get you on the right track.

3. Mar 29, 2005

### Chi Meson

Another point to remember:
In perfect circular motion, the only unbalance force is the centripetal force. The centripetal force must be provided by a recognizable force (or component thereof) such as friction, tension, normal force, etc.

That makes the centripetal force also the net force. This means all other forces (or componants) that are not pointing toward the center of the circle, must balance.