1. Circular Motion Things that Travel in a CIRCLE!!

2. Axis: A straight line around which circular motion takes place Rotation: When an object turns about an “internal” axis (an axis located within the body of the object), also called spin Revolution: when an object turns around an “external” axis (an axis not necessarily connected to the body)

3. Rotational Speed (Angular Speed): number of rotations per unit of time It is expressed in revolutions per minute RPM Tangential Speed: is directly proportional to rotational speed and the distance from the axis (kinda like “regular” speed)

4. Centripetal Force: any force that causes a body to move in a circular path or in part of a circular path, such as rounding a corner The only force exerted on an object moving in a circular path is directed toward the center of circular motion

5. Centrifugal Force: name given to a outward-acting force, and it is useful only in a rotating system It is different from a real force in that there is no interaction (pair of forces), there is no mass out there pulling on it There is no reaction counterpart to the centrifugal force that is felt, therefore it is not a real force

6. F c (Centripetal Force) a c (centripetal acceleration) What do you think these mean? Basically that the object is moving with circular motion

7. New formulas Quantity UnitFormula CentripetalNF c = ma c Centripetalm/s 2 a c = v 2 /r acceleration Force

8. Example A 0.25 kg mass is attached to a 1.00 m length of string. The mass is moving in a horizontal circle at a speed of 15.0 m/s. What is the centripetal force acting on the mass?