[precisionscott]

I took a look in my sisters physics book (high school), and it was saying that there is no such thing as centrifugal force. I would like to see what you guys thought. Here is an excerpt:

From Physics book:

A ball being swung in a circle has a force acting on it to give it "Centripetal acceleration". It is this force that causes it to go in a circle. The force is acting perpendicular to the ball if it moves in a circle is pointing to the center of the circle. Therefore, centripetal force acts from the ball to the center of the circle, not along the circumference. To make the ball go in a circle, an outside force (person swinging ball on a string) is required. The common misconception is that an object moving in a circle has an outward force, so-called "centrifugal force". "This is incorrect".

As an example, a car going in a circle has centripetal acceleration. There is no centrifugal force pulling on you. What is happening is you tend to move in a straight line, whereas the car is following a curved path. For the passenger in the car to follow the curve also, a force (friction on the seat cushion or the door) is exerted. The car requires an inward force to keep it in the curve. This force is supplied by friction between tires and pavement. If friction is not great enough, you end up in ditch!! A banked curve reduces the amount of friction needed to keep car on curve.

Centripetal describes the direction of the force - towards the center of the circle. (Centripetal is defined as aiming toward the center).
Centrifugal force is a force defined as "center-fleeing". There is no such force according to this book. All forces are acting toward the center not away from the center.