The centripetal force is not a physical force but rather the component of the force which points towards the center during circular motion. For the example of the Ferris wheel, the centripetal force depends on the position. For instance, if the the person is on the top of the ferris wheel, the gravitational and the normal force combined is the centripetal force, but if the person is in the bottom of the ferris wheel, the normal force minus the gravitational force is the centripetal force.
The net force of a car moving around a bank curved is not zero, rather, because the net force is always pointing perpendicular to the velocity, the motion is circular and hence the car never moves toward or away from the center.
Assuming that you mean a "ferris" wheel:
In a ferris wheel, $\frac{m*v^2}{r}$ is very small, because ferris wheels move slowly.
Also, on the wheel, all of the cars with people remain upright. This means that the force of gravity is always pulling downwards on people as they ride.
So, there are three cases that you can look at to explain this:
- You are at the top.
In this case, the centripetal force (which is required to keep you moving within the circle is provided by gravity. Gravity pulls you down towards the center of the wheel.
- You are at the bottom.
In this case, the force provided is an upward force provided by the metal structure of the wheel. The metal beams that support the car as it travels along at this point.
- You are on the side.
In this case, the force towards the center of the wheel is provided by a combination of the structure of the wheel (if you are on the bottom/side, and gravity if you are more on the top)
Best Answer
I think you are confusing motion and acceleration. Forces determine the acceleration of an object, not the motion at that instant.
The car at the top is accelerating downward, and the car at the bottom is accelerating upward. But they also have velocity in the sideways direction