physics
posted by Bella on .
there are 3 parts to my question. i need help on the last part.
1.a. A child rides a bike in a circular path with a radius of 2.0 m. The tangential speed of the bike is 2.0 m/s. The combined mass of the bike and the child is 43 kg. What is the magnitude of the bike's centripetal acceleration?
i got 2.0 m/s^2
b., What is the magnitude of the centripetal force on the bike?
i got 86 N
c. What kind of force provides the centripetal force on the bike?
i don't know,... gravitational force, friction, air resistance, or normal force
thanks for the help!

c. A centripetal friction force on the wheels, applied at the ground and perpendicular to the direction of motion, provides the force that keeps the bike going in a circle
Spokes provide the centripetal force toward the axle of the wheel, but they did not ask for that. 
so friction

Friction in a particular sideways direction. There is also forward/backward friction when accelerating, decelerating or climbing hills